A POPULAR 



TREATISE ON "GEMS. 




IvSib.Berd. 2 Emeiald. liKubelliie. 1< Brazil Topaz, . 5.\iiiy.irc-on . 
OStai- Sajjphire. 7Koh i no or. 



'^ 



A POPULAR 



TREATISE ON GEMS, 



m REFERENCE TO THEIR 



SCIENTIFIC VALUE: 

A GUIDE FOR THE TEACHEfi OF NATUKAL SCIENCES, 



THE 



LAPIDARY, JEWELLER, AND AMATEUR: * 



TOGETHER WITH A 



DESCRIPTION OF THE ELEMENTS OF MINERALOGY, AND ALL 
ORNAMENTAL ANEl ARCHITECTURAL MATERIALS. 



Witfe tfkpnt lltostrattous. 



BY 

DE. Lf'TEUCHTWAl^GEK, 

CHEMIST AND MINERALOGIST, MEMBER OF THE NEW YORK LYOETTM OF 
NAT. HIST., AMERICAN ASSOC. OP SCIENCE, OF THE 
MINEKALOGICAL SOCIETIES OF JENA, 
, ALTBNBUEG, ETC. 



NEW YOEK: 

D. APPLETON & COMPANY, 846 & 348 BROADWAY. 

1859. 



Entered according to Act of Congress, in the year 1859, 

By DE. L. FE.UCIITW anger, 

In the Clerk's Office of tiie District Court of the United States foj* the Southern 
District of New York. 



7 



f 




^H 



V 



PREFACE. 



In none of the numerous .works on Mineralogy that have 
lately been published, have Gems been treated in a manner 
commensurate with the important rank which they hold in the 
mineral kingdom. The author of this treatise pubhshed in 
1838 a small work on Gems, which was well received by the 
scientific world. As that edition was soon disposed of, the 
author intended to issue a larger and improved edition, but 

^close application to his legitimate pursuits prevented him from 
accomplishing that object. In 1851 he visited the London 
Exhibition, where the treasures of the mineral kingdom, and the 
profusion of brilliant and costly gems from all quarters of the 
globe, formed a collection such as had never before been wit- 
nessed ; and he then resolved to embody the facts which he 
had there collected in a new work on Gems, v^'hich he has been 
, encouraged to publish by the solicitations of numerous teachers 
and jewellers, who had used his former treatise as a work of 
reference, and who wish to have a work that will impart useful 
and correct information in regard to the locality and value of 
Gems in the present state of scientific knowledge. As a work 

• on Gems would be incomplete without a treatise on Mineralogy, 
and as the author did not wish to enter into details foreign to 
his subject, he wa§ at a loss how to commence ; but on consult- 
ing the recent works on the Elements of Mineralogy of Prof. 
Nichols and Zimmerman, he was convinced that a summary 



6 PREFACE. 

of the leading principles of Mineralogy was indispensable, as an 
introduction to his main design ; and that Ciystallography, the 
mother of Gems, should be explained, before treating them when 
prepared for the dealer or wearer : he concluded, therefore, to 
commence his treatise by following the Terminology of Nichols' 
Elements of Mineralogy, of which he copied the greater part, 
along with some remarks of Dafresnoy, from the study of whose 
gieat work on Mineralogy he derived much valuable informa- 
tion. He feels it incumbent on him publicly to acknowledge 
his obligations to the author of the Elements of Mineralogy, 
for the concise and lucid descriptions contained in the first 
part of that work, which should be read by every student of 
Mineralogy. In the second part of this work, which treats of 
Gems, the" author has followed his own system in their classifi- 
cation ; that is, he has arranged them according to their in- 
trinsic value, and not alphabetically, as has been done by some 
authors, nor as oxydized stones — a system adopted by others. 
The diamond is placed at the head of the whole class of Gems, 
and the others follow in the order of their commercial value. 
Some minerals which are not properly Gems have been in- 
cluded in the list, either on account of certain specific characters 
which they possess, or their applicability to some useful purpose. 
Many mineral substances which belong properly to the geolog- 
ical or economical department of the science of mineralogy, 
have been treated in this part of the work ; but they occupy 
so important a position in the economy of life, that their intro- 
duction cannot be regarded as an intrusion. Keference is here 
made to the detailed account of coal, marble, granite, and 
sienite — are they not as valuable as the Gems described in this 
treatise ? are they not the foundation on which is to be reared 
the opulence of future generations? have they not already 
contributed to the aggrandizement of the United States, the 
most enterprising nation on the globe ? 

The revenue arising from the annual production of eight 



PKEFACE. 7 

million tons of coal is not inconsiderable. The marble of the 
country, which is just beginning to be developed, bids fair to 
compete with that of stny other country, and to revolutionize 
the civilized world. The marble from California, that from 
the quarry lately discovered in Pennsylvania, the Leocadia 
Bieccia, the Yerde- Antique of Vermont, and the white marble 
from Canaan, Conn., which is used in the construction of the 
Fifth Avenue Hotel, Madison Square, N. Y., are referred to as 
illustrations. Are not the sienites and the granites which 
have been quarried for the last fifty years, and which have been 
used in the erection of all our public edifices, really as valuable 
as G^ms ? 

Few persons were aware, until recently, of the existence of 
fancy (variegated) marbles in this country ; and Italy, Greece, 
and Ireland furnish the materials for ornamenting fine houses 
and cemeteries, because our own resources have been overlooked, 
"or not developed. What will be the condition of things fifty 
years hence, when the fine arts will occupy as prominent a po- 
sition in this country as in any other, and when wealth and 
taste will compete with the arts and sciences for the ascendency ? 
The Almighty has converted the vegetables of the forest into a 
mineral substance, the animals of the sea into building-stone, 
and endowed man with the faculty of exploring and developing 
the hidden treasures of nature, and this faculty will soon render 
this country independent of all other nations. The principal 
aim of the author has been to explain not only the useful, but 
also the ornamental mineral substances, and such compositions 
called mosaics as are prepared from them, and he is indebted 
for much valuable information pertaining to this branch of the 
subject to the Jury Report of the London Exhibition. 

A prominent place has been assigned to pearls, both genuine 
and artificial, for the reason that shells containing pearls are 
found in many fresh-water streams in the United States, some 



o PREFACE. 

of which may prove as profitable to the explorer as the dis- 
covery near Paterson, N. J., ia 1857. 

• 

The colored illustrations of the most important minerals, 
which are used for ornamental purposes, have been taken from 
a splendid work by J. G. Kurr, For the illustration of dia- 
monds, both rough and cut, he has made free use of the French 
work of Charles Barbot, which also contains a description of 
whatever was curious or unique in the Paris Exhibition of 1855. 
Dana's Mineralogy, Booth's Encyclopedia, Hitchcock's Report 
on the Geology of Massachusetts, the New York State Report, 
and the Report of the New York Exhibition, 1853, have been 
consulted in the preparation of this treatise. 

To his fiiend Charles Legendre, Esq., many acknowledgments 
are due for the beautiful designs of the frontispiece, and the 
various explanatory drawings, and to Dr. James R. Chilton for 
the use of his beautiful Zircon and American marbles. The* 
artists, Messrs. Robertson, Seibert & Shearman, deserve the 
highest praise for the faithful manner in which they have exe- 
cuted the work ; as also Mr. Schnapauff, who colored the plates 
with great care and precision. 

The author trusts that his humble efforts may be appreciated 
by the teacher, the jeweller, and the public at large, and that 
it may find favor with the student and amateur. 



CONTENTS. 



Page 
Introduction ^^, 13 



FAET I. 

TERMINOLOGY. 

CHAPTEE I.— Form of minerals 19 

" . II. — Physical properties of minerals 75 

" III. — Chemical properties of minerals 102 

" lY. — Classification of minerals 129 

PAKT II. 

THE GEMS. 

Division of Gems 135 

Color, gravity, and hardness 137 

Chemical characters 139 

Composition 139 

Artificial production of Gems and Minerals 140 

Geological characters 145 

Geographical distribution 146 

Practical division and nomenclature 147 

History of Gems 148 

Sculpture in Gems 151 

On Grinding 153 

Forms of the diamond 161 

Form of Gems 163 

Common lapidary 166 

Engraving .....; 166 

Sawing and drilling Gems 168 

1* 



10 CONTENTS. 

Page 

Grinding and polishing materials 168 

Heightening the color of Gems 169 

Setting of Gems 171 

Cleaning Gems 172 

Imitations of Gems 172 

Price of, and trade in Gems .-. 181 

Gems for optical purposes. 181 

PART III. 

CONSIDEEATION OF THE INDIVIDUAL GEMS. 

Diamond 183 

Corundum 214 

Sapphire 214 

Common corundum 223 

Chrysoberyl, Cymophane 225 

Spinelle ' 227 

Topaz : 229 

Euclase. . ." *. 234 

Emerald 235 

Beryl, aquamarine -. ' 240 

Zircon. Hyacinth, Jargon 244 

Garnet 247 

Essonite, Cinnamon-stone 253 

Tourmaline, Eubellite, Siberite 254 

Quartz 259 

Kock crystal 260 

Amethyst ^ 266 

Common quartz — rose quartz 2691 

" '' Cat's eye 270 

" " Prase 271 

'• " Avanturine 272 

Jasper 273 

Hornstone . . . .< 277 

Chalcedony 277 

Carnelian 279 

Heliotrope, Bloodstone 282 

Agate 283 

Chrysoprase 292 



CONTENTS. 1 1 

Page 
Chrysolite, Peridot, Olivin * ; . 294 

Isolite *............ 297 

Opal 299 

Fire opal 304 

Hydrophane 305 

Semi-opal 306 

Cachelong 307 

Jasper opal 308 

Obsidian .* : 309 

Axinite » 311 

Felspar 812 

Adularia .' 312 

Commou felspar 315 

Labrador ._ 317 

Hypersthene • • • 320 

Idocrase 321 

Hauyne 322 

Lapis lazuli 322 

Kyanite, Sappare, Disthene 327 

Turquoise 329 

Natrolite 332 

Fluor spar * 333 

Malachite 335 

Satin spar 340 

Alabaster. •. 341 

Amber 343 

Jet ■ 353 

Meerschaum 357 

Lava 360 

Jade 361 

Serpentine -362 

Marble 364 

Stalactite and Stalagmite 380 

Egyptian and Italian marbles 382 

American marbles 383 

Pisolite and Oolite 386 

Eock of Gibralter 386 

Apatite 387 

Lepidolite 389 

Mica 389 



1 2 CONTENTS. 

Pyrites : 390 

Rose manganese * 391 

Porphyry 391 

Sienite 393 

Granite. ; 396 

Pearls 400 

Corals 419 

Shell cameos 425 

Mosaic and Pietra Dura 426 



INTRODUCTION. 



The natural productions of our globe may be considered 
either in their original or in their changed condition. They 
are divided into two general classes which are -determined, 
■ — either by certain characters that do not require explana- 
tion or investigation, — or, by the external appearances 
which are presented by them in their altered condition, 
and by investigating the causes which produced the changes 
of form or state. 

In the former case, the science is called Natural History; 
in the latter, Natural Philosophy. 

Natural History, considered in reference to the original 
properties of natural productions, must, therefore, be di- 
vided into organic and inorganic: to the former belong 
Zoology and Botany; to the latter. Mineralogy. 

Botany and Zoology comprise bodies possessed of vitality, 
or beings which, increasing by the absorption of nutritive 
substances, mature after a certain period ; their parts are 
dependent upon each other, and they cannot be separated 
without destroymg the integrity of the individual, which, ' 
after a certain period, loses its vitality and ceases to exist ; 



1 4 INTBODUCTION. 

or death ensues, decomposition takes place, and the original 
being is entirely destroyed. 

Mineralogy, on the contrary, comprises those natural 
objects which are not possessed of life,, and do not increase 
by absorption, but merely by accretion — that is, by an ex- 
ternal growth or addition without any assimilation ; they 
do not mature by age ; their parts may be separated with- 
out destroying their individuality; and their formation 
being the result of chemical attraction, they are not liable 
to decomposition. 

Mineralogy comprises two distinct sciences : Mineralogy 
proper, which treats of the simple minerals, either as inde- 
pendent bodies, or in relation to the characters which serve 
to determine and distinguish them ; and Geology, which 
considers both simple and mixed minerals as they exist in 
nature, and in their dependent relations with soils and 
rocks. Mineralogy describes the individual qualities of the 
several mineral species, — Geology treats of them only as 
associated in the structure of the earth. 

The characters of minerals are ascertained by their mor- 
phological, physical, and chemical properties. That part of 
Mineralogy which treats of the application of minerals to 
the different arts, is called Economical Mineralogy ; miner- 
als used by lapidaries in making ornaments, are called Gems. 

Geometry, Physics (Natural Philosophy), and Chemistry, 
form the base for the study of Mineralogy, as without a 
knowledge of those sciences, the true characters of a min- 
eral cannot be ascertained. 

Geology is, according to Lyell's explanation, the science 
which investigates the successive changes that have taken 
place in the organic and inorganic kingdoms of nature. It 



INTEODUCTION. 16 

inquires into the causes of these changes, and the influence 
which they have exerted in modifying the surface and ex- 
ternal structure of our planet. By these researches into 
the state of the earth and its inhabitants at former periods, 
we acquire a' more perfect knowledge of its present condi- 
tion, and more comprehensive views concerning the laws 
now governing its animate and inanimate productions. 
When we study history, we obtain a more profound in- 
sight into human nature, by instituting a comparison be- 
tween the present and former states of society. We trace 
the long series of events which have gradually led to the 
actual posture of affairs, and by connecting effects with 
their causes, we are enabled to classify and retain in the 
memory a multitude of complicated relations, the various 
peculiarities of national character, the different degrees of 
.moral and intellectual refinement, and numerous other cir- 
cumstances, which, without historical associations, would 
be uninteresting or imperfectly understood. When we 
carry back similar relations into the history of nature, we 
likewise investigate nature's operations in former epochs. 

The form of a coast, the configuration of the interior of 
a country, the existence afid extent of lakes, valleys, and 
mountains, can often be traced to the former prevalence of 
earthquakes and volcanoes in regions which have long been 
undisturbed. To these remote convulsions the present fer- 
tility of some districts, the sterile character of others, the. 
elevation of land above the sea, the climate, and various 
peculiarities, may be distinctly referred. Many distinguish- 
ing features of the surface of the earth may often be as- 
cribed to the operation, at a remote era, of slow and tran- 
quil causes, to the gradual deposition or sediment in a lake 



16 INTRODUCTION. 

*• 

or in the ocean, or to the prolific increase of testacea and 
corals. We also find in certain localities subterranean de- 
posits of coal, consisting of vegetable matter formerly- 
drifted into seas and lakes. These seas and lakes have 
since been filled up, the lands whereon the forests grew 
have disappeared or changed their form, the rivers and 
currents which floated the vegetable masses can no longer 
be traced, and the plants belonged to species which for ages 
have passed away from the surface of our planet, yet the 
commercial prosperity and numerical strength of a nation 
may now be mainly dependent on the local distribution of 
fuel determined by that ancient state of things. Geology 
is intimately connected to almost all physical sciences, as 
history is to the moral. An historian should, if possible, 
be profoundly acquainted with ethics, politics, jurispru- 
dence, the military art, theology, and with all branches of 
knowledge, by which an insight into human affairs, or into 
the moral and intellectual nature of man, can be obtamed. 
No less desirable is it for a geologist to be well versed in 
chemistry, natural philosophy, mineralogy, zoology, com- 
parative anatomy, botany, and every science relating to 
organic and inorganic nature.* Having such accomplish- 
ments, the historian and geologist would rarely fail to draw 
correct and philosophical conclusions from the various 
monuments transmitted to them from former occurrences. 
, They would know to what combination of causes analogous 
effects were referable, and would often be enabled to sup- 
ply by inference information concerning many events unre- 
corded in the defective archives of former ages. 

Mineralogy is sometimes understood as comprising the 
natural history of every portion of inorganic nature. Here 



INTRODUCTION. l7 

we consider it as limited to the natural history of simple 
minerals, or mineral species. In the strictest sense, a min- 
eral species is a natural inorganic body, possessing a defi- 
nite chemical composition, and assuming a regular deter- 
minate form, or series of forms. Many substances hereto- 
fore regarded as minerals will naturally be excluded — such 
as all the artificial salts, the inorganic secretions of plants 
and animals, the remains of former living beings now im- 
bedded in rocks. Many substances originally organic pro- 
ducts have by common consent found a place in mineral 
systems — such as coal, amber, and mineral resins — which 
ought not to be the case ; alsQ some amorphous substances, 
with no forms or chemical composition, as some kinds of 
clay, have also been introduced into works on Mineralogy, 
but often improperly, and with no beneficial result. Aggre- 
gates of simple minerals or rocks are likewise excluded from 
the science of Mineralogy, though the various associations 
of minerals, their modes of occurrence, and their geologi- 
cal position, are important points in the history of the dif- 
ferent species. One most important object in Mineralogy is 
a full description of minerals, their essential properties and 
distinctive characters, as will enable the student to distin- 
guish the various species, and to recognize them when they 
occur in nature. 

The gems, or precious stones, are obtained from miner- 
als. It is indispensable, therefore, to be fully acquamted 
with all the characters which distinguish them from one 
another, which is accomplished by the terminology or no- 
menclature of the science of Mineralogy — that is, with the 
meaning of the terms used in describing the properties of 
minerals, and the various modifications they may undergo, 



18 INTKODUCrnON. 

and also an account of the properties themselves. The 
system of classification is another closely related portion of 
Mineralogy. It gives an account of the order in which the 
mineral species are arranged. A third and most important 
part of Mineralogy is the physiography of the various 
species — giving an account of their characteristic marks, 
and a description of their appearance or external aspect 
and forms, their principal physical and chemical properties^ 
their mode of occurrence, with their geological and geo- 
graphical distribution, and their various uses, whether in 
nature or whether in the arts, or as gems for ornamental 
purposes. . 



PART I. 

TERMINOLOGY 



■»♦» 



CHAPTER I. 

FORM OF MINERALS. 



The physical properties of a mineral comprise all those 
properties belonging to it as a body existing in space, and 
consisting of matter aggregated in a peculiar way. The 
more important of these are, — its form as shown in crystal- 
lization ; its structure as determining its mode of cleavage 
and fracture ; its hardness and tenacity ; its weight or spe- 
cific gravity ; and its relations to light, heat, electricity, and 
magnetism. 

Crystalline and Amorphous. — Mineral substances occur 
in two distinct modes of aggregation. Some "consist of 
minute particles simply collected together, with no regu- 
larity of structure or constancy of external form, and are 
named amorphous. All fluid minerals are in this condition, 
together with some solid bodies, which appear to have con- 
densed either from a gelatinous condition like opal, when 
they are named porodine^ or from a state of igneous fluidity 
like obsidian and glass, when they are named hyaline. The 
other class have their ultimate atoms evidently arranged 
according to definite law, and are named crystalline^ when 
the regularity of structure appears only in the internal dis- 



2Q A PRACTICAL TREATISE OK GEMS. 

position of the parts ; and crystallized^ when it also produces 
a determinate external form, or a crystal. 



CRYSTALS. 

Faces^ JEdges^ Angles^ Axes of Crystals. — ^The word 
crystal in mineralogy designates a solid body exhibiting an 
original (not artificial) more or less regular polyhedric form. 
It is thus bounded by plane surfaces, named faces^ which 
intersect in straight lines or edges^ and these again meet in 
points and form solid angles^ bounded by three or more 
faces. The sj^ace occupied by a crystal is often named a 
form of crystallization., which is thus the mathematical 
figure regarded as independent of the matter that fills it. 
Crystals bounded by equal and similar faces are named 
simple forms ; while those in which the faces are not equal 
and similar are named compound forms., or combiyMtions., 
being regarded as produced by the union or combination of 
two or more simple forms. The cube or hexahedron (fig. 
1), bounded by six equal and similar squares.; the octahe- 
dron (fig. 2), by eight equilateral triangles ; and the rhora- 
bohedron, by six rhombs, — are thus simple forms. An axis 
of a crystal is a Une passing through its centre and termi- 
nating either in the middle of two faces, or of two edges, or 
in two angles ; and axes terminating in similar parts of a 
crystal are named similar axes. In describing a crystal, one 
of its axes is supposed to be vertical or upright, and is then 
named the principal axis., and that axis is chosen which is 
the only one of its kind in the figure. A few other techni- 
cal terms used in describing crystals will be explained as 
they occur. 

Systems of Crystallization. — The forms of crystals that 
occur in nature seem almost innumerable. On examining 
them, however, more attentively, certain relations are dis- 



FOKM or MIlSrEEALS. 



. 21 



covered even between highly complex crystals. When the 
axes are properly chosen, and placed in a right position, the 
various faces are observed to group themselves in a regular 
find beautiful manner around these axes, and to be all so 
related as to compose connected series produced according 
to definite laws. In every mineral species there is a certain 
form of crystal from which, as a primary, every other form 
of crystal observed in that mineral species may be deduced. 
In each species the axes, bearing to each other definite 
numerical proportions, intersect at angles which are constant. 
So also the faces of the various forms are related to each 
other, and to their primary, according to certain definite 
laws. When viewed in this manner, and referred to their 
simplest forms, the innumerable variety of crystals occurring 
in nature may all be reduced to six distinct groups, or, as 
they are named, systems of crystallization. The following 
are the names given to* these systems of crystallization in 
some of the best authors : 





Naumann. 


Mohs. 


Weiss and G. Eose. 


1. 


Tesseral System. 


Tessular. 


Regular. 


2. 


Tetragonal System. 


Pyramidal. 


2 and 1 axial. . 


3. 


Hexagonal System. 


Rhombohedral. 


3 and 1 axial. 


4. 


Ehombic System. 


Orthotype. 


1 and 1 axial. 


&. 


Monoclinohedric System. 


Hemiorthotype. 


2 and 1 membered 


6. 


Triclinohedric System. 


Anorthotype. 


1 and 1 membered 



In the following treatise the terminology of Naumann is 
adopted, his method of classifying and describing crystals 
appearing the simplest and best adapted to promote the 
progress of the student. 

ITolohedric and Hemihedric. — Before describing these 
systems, it must be observed that certain crystals appear as 
the half of others, and are therefore named hemihedric; 
while the crystals with the full number of faces are named 
holohedric. Hemihedric crystals are formed Avhen the alter- 



22 



A PRACTICAL TREATISE ON GEMS. 



nate faces or groups of faces of a hololiedric crystal increase 
symmetrically, so as to obliterate the other faces. Thus, 
if four alternate faces of the octohedron increase so as to 
obliterate the other four, a tetrahedron with half the num- 
ber of faces is formed. 

I. The first, or Tesseral System^ named from tessera^ a 
cube, which is one of the most frequeiit varieties, is charac- 
terized by three equal axes inters'ecting each other at right 
angles. Properly speaking, this system has no chief axis, 
as any one of them may be so named, and placed upright 
in drawing and describing the crystals. Of these there are 
thirteen varieties, which are thus classed and" named from 
the number of their faces : 

1. One Tetrahedron, or form with four faces. 

2. One Hexahedron, with six faces. 

3. One Octahedron,'with eight faces. 

4. Four Dodecahedrons, with twelve faces. 

5. Five Icositetrahedrons, with twenty-four faces. 

6. One Tetracontaoctahedron, with forty-eight faces. 

The dodecahedrons are further distinguished, according 
to the form of their faces, into rhombic, trigonal, deltoid, 
and pentagonal dodecahedrons ; and some of the icositetra- 
hedrons have also received peculiar names. 





Fig. 1. 



Fig. 2. 



FOKM OF MINEEALS. 



23 



The following is a description, with figures, of the differ- 
ent forms above mentioned, beginning with 
The Holohedric forms. 

1. The hexahedron or cube (fig. 1) is bounded by six 
equal squares, has twelve edges, formed by faces meeting 
at 90°, and eight trigonal angles. The principal axes join 
the centre points of any two opposite faces. — Examples are 
fluor spar, galena, boracite. 

2. The octahedron (fig. 2), bounded hj eight equilateral 
•triangles, has twelve equal edges, with planes meeting at 

109° 28', and six tetragonal angles. The principal axes 
join the opposite angles, two and two. — Example, alum, 
spinel, magnetic iron ore. 

3. The rhombic- dodecahedron (fig. 3) is bounded by 
twelve equal and similar rhombs (diagonals as 1 andv^2), 





Fig. 8. 



Fig., 4. 



has twenty-four equal edges of 120°, and six tetragonal and 
eight trigonal angles. The principal axes join two opposite 
tetragonal angles. — Ex., garnet, boracite. 

4. The tetrakishexahedrons (variety of icositetrahedron, 
fig. 4) are bounded by twenty-four isosceles triangles, ar- 
ranged in six groups of four each. They have twelve longer 
edges which correspond to those of the primitive or in- 



24 A PRACTICAL TREATISE ON GEMS. 

scribed tube, and twenty-fonr sliorter edges placed over 
each of its faces. The angles are eight hexagonal and six 
tetragonal ; the latter joined two and two by the three prin- 
cipal axes. This form varies in general aspect, approach- 
ing, on the one hand, to the cube ; on the other, to the rhom- 
bic dodecahedron. — Ex., flnor spar, gold. 

5. The triakisoctahedrons (variety of icositetrahedron, 
%. 5) are bounded by twenty-four isosceles triangles, in 
eight groups of three, and, like the previous form, vary in 
general aspect from the octahedron on one side, to the* 
rhombic-dodecahedron on the other. The edges are twelve 
longer, corresponding Avith those of the inscribed octahe- 
dron, and twenty-four shorter, three and three over each 
of the faces. The angles are eight trigonal and six dite- 
tragonal (formed by eight faces) ; the latter angles joined 
two and two by the principal axes. — ^Ex., galena, diamond. 





Fig. 5. Fig. 6- 

6. The icositetrahedrons (most common variety, fig. 6) 
are bounded by twenty-four deltoids or figures with four 
eides, of which two and two adjacent ones are equal. This 
form varies from the octahedron to the cube, sometimes 
approaching the former and sometimes the latter in general 
aspect. The edges are twenty-four longer and twenty- 
four shorter. The angles are six tetragonal joined by the 



foem'of minerals. 25 

principal axes, eight trigonal, and twelve rhombic, or tetra- 
gonal with unequal angles. 

1. The hexakisoctahedrons (fig. 7), bounded by forty- 
eight scalene triangles, vary much in general aspect, ap- 
proaching more or less to all the preceding forms ; but 
most frequently they have the faces arranged either in six* 
groups of eight, or eight of six, or twelve of four faces. 
There are twenty-four long edges, often corresponding to 
those of the rhombic-dodecahedron ; twenty-four interme- 
diate edges lying in pairs over each edge of the inscribed 
octahedron ; and twenty-four short edges in pairs over the 
edges of the inscribed cube. There are six ditetragonal 
angles joined by the principal axes, eight hexagonal and 
twelve rhombic angles. — Ex., fluor spar, garnet, diamond. 



Fig. 7., 

The seven forms of crystals now described are related to 
each other in the most intimate manner. This will appear 
more distinctly from the following account of the derivatign 
of the forms, with which is conjoined an explanation of the 
crystallographic signs or symbols by which they are desig- 
nated. We have adopted these symbols throughout this 
work, in the belief that they not only mark the forms in a 
greatly abbreviated manner, but also exhibit the relations 
of the forms and combinations in a way which words could 
hardly accomplish. 



26 . A PRACTICAL TREATISE ON GEMS. 

The derivation of forms is that process by which, from 
one form chosen for the purpose, and considered as the 
type — the fundamental or primary form — all the other 
forms of a system may be produced, according to fixed prin- 
ciples or general laws. In order to understand this process 
or method of derivation, the student should keep in mind 
that the position of any plane is fixed when the positions 
of any three points in it, not all in one straight line, are 
known. To determine the position, therefore, of the face 
of a crystal, it is only necessary to know the distance of 
three points in it from the centre of the crystal, or the 
-points in which the face or its supposed extension would in- 
tersect the three axes of the crystal. The portion of the 
axes between this point and the centre are named parame- 
ters, and the position of the face is sufficiently known when 
the relative length or proportion of these parameters is 
ascertained. When the position of one face of a simple 
form is thus fixed or described, all the other faces are in 
like manner fixed, since they are all equal and similar, and 
all intersect the axes in a uniform manner ; and the expres- 
sion which marks or describes one face, marks and describes 
the whole figure. 

The octahedron is generally adopted as the primary or 
fundamental form of the tessera! system, and distinguished 
by the first letter of the name, O. Its faces cut the half 
axes at equal distances from the centre ; so that these semi- 
axes, or the parameters of the faces, have to each other the 
proportion 1:1:1. In order to derive the other forms 
from the octahedron, . the following construction is era- 
ployed. The numbers refer to the descriptions above. 

Suppose a plane so placed in each angle of the octahe- 
dron as to be vertical to the axis passing through that 
angle and consequently parallel to the two other axes (or 
to cut them at an infinite distance =00); then the hexa- 



FORM OF MINEEALS. 27 

liedron or cube (l) is prodiiced, designated by the crystal- 
lographic sign oo O oo ; expressing the proportion of the 
parameters of its faces, or oo : oo : 1. If a j^lane is sup- 
posed placed in each edge parallel to one axis, and cut- 
ting the two other axes at equal distances, the resulting 
figure is the rhombic dodecahedron (3), designated by the 
sign 00 O, the proportion of the parameters of its faces be- 
ing 00 : 1 : 1. The triakisoctahedron (5) arises when on 
each edge of the octahedron planes are placed cutting the 
axis not belonging to that edge at a distance from the cen- 
tre ^7i which is a rational number greater than 1. The 
proportion of its parameters is therefore mil : 1, and its 
sign mO ; the most common varieties being f O, 20, and 
30. When, on the other hand, from a similar distance m 
in each two semiaxes prolonged, a plane is di'awn to the 
other semiaxis, or to each angle, an ikositetrahedron (6) is 
formed ; the parameters of its faces have consequently the 
proportion w?- : 1 : m* and its sign is raOra • the most com- 
mon varieties being 202 and S03, the former very frequent 
in leucite, analcime, and garnet. When, again, planes are 
drawn from each angle, or the end of one semiaxis of the 
octahedron, parallel to a second axis, and cutting the third 
at a distance w, greater than 1, then the tetrakishexahedron 
(4) is formed, the parameter of its faces oo : 1 : n ; its sign 
ooO?z; and the most common varieties in nature ooOJ, 
00 02, and oo03. Finally, if in each semiaxis of the octa- 
hedron two distances, m and n^ be taken, each greater than 
1, and m also greater than n^ and planes be drawn from 
each angle to these points, so that the two planes lying 
over each edge cut the second s"emiaxis belonging to that 
edge, at the smaller distance w, and the third axis at the 
greater distance m, then the hexakisoctahedron (7) is pro- 
duced, the parameters of which are m : n : 1, its sign mOw, 
and the most common varieties 30f , 402, and 50|-. 



28 A PEACTICAJL TEEATISE ON GEMS. 

The next class of crystals are the semi-tesseral forms ,' and 
first, those with oblique faces, often named tetrahedral, from 
their relation to the tetrahedron. (1.) This form (fig. 8) 





Fig. 8. Fig. 9. 

is bounded by four equilateral triangles, has six equal edges 
with faces meeting at 70° 32', and four trigonal angles. 
The principal axes join the middle points of each two op- 
posite edges. — Ex., gray-copper ore, boracite, and telvine. 
(2.) The trigonal dodecahedrons (fig.* 9) are bounded by 
twelve isosceles triangles, and vary in general form from 
the tetrahedron to the hexahedron. There are six longer 
edges corresponding to those of the inscribed tetrahedron, 
and twelve shorter placed three and three over each of its 
faces ; and four hexagonal and four trigonal angles. — Ex., 
gray-copper ore, and bismuth-blende. (3.) The deltoid- 
dodecahedrons (fig. 10) are bounded by twelve deltoids, 
and vary in general form from the tetrahedron on the one 
hand, to the rhombic-dodecahedron on the other. They 
have twelve longer edges lying in pairs over the edges of 
the inscribed tetrahedron ; and twelve shorter edges, three 
and three over each of its faces. The angles are six tetra- 
gonal (rhombic), four acute trigonal, and four obtuse tri- 
gonal angles. The principal axes join two and two oppo- 
site rhombic angles. — Ex., gray-copper ore. (4.) The hex- 
akistetrahedrons (fig. 11) are bounded by twenty-four 



FORM OF MINERALS. 



29 



scalene triangles, and most commonly have their faces 
grouped in four systems of six each. The edges are twelve 
shorter and twelve longer, lying in groups of three over 





Fig. 10. 



Fig. 11. 



each face of the inscribed tetrahedron, and twelve interme- 
diate in pairs over its edges. The angles are six rhombic, 
joined in pairs by the principal axes, and four acuter and 
four obtuser hexagonal angles. — Ex., diamond. 

The derivation and signs of these forms are as follows : — 
The tetrahedron arises when four alternate faces of the 
octahedron are enlarged, so as to obliterate the other four, 

aChd its sign is hence — . But, as either four faces may'^be 

thus enlarged or obliterated, two tetrahedrons can be formed 
similar in all respects except in position, and together mak- 
ing up the octahedron. These are distinguished by the 
signs + and — , added to the above symbol, but only the 

latter in general expressed thus — — . In all hemihedric 

systems two forms similarly related occur, which may thus 
be named complementary forms. The trigonal dodecahe- 
dron is derived from the icositetrahedron, by the expansion 

of the alternate trigonal groups of faces. Its sign is — - — , 



30 



A PEACTICAL TREATISE ON GEMS. 



triakisoctahedron, and its sign is 



Lastly, the hexakis- 



-. . 202 , 
the most common variety bemg — ^, lound m gray-copper 

ore. The deltoid-dodecahedron is in like manner the result 
of the increase of the alternate trigonal groups of faces of the 

'Y' 

tetrahedron arises in the development of alternate hexa- 
gonal groups of faces in the hexakisoctahedron, and its sign 

. mOn 
IS — -— . 

2 

The parallel-faced semitesseral forms are two. (1.) The 
pentagonal dodecahedrons (fig. 12) are bounded by twelve 





Fig. 12. 



Fis. 13. 



symmetrical pentagons, and vary in general aspect be- 
tween the hexahedron and rhombic-dodecahedron. They 
have six regular (and in general longer) edges, lying 
over the faces of the inscribed hexahedron, and twenty- 
four generally shorter (seldom longer) edges, usually lying 
in pairs over its edges. The angles are eight of three equal 
angles, and twelve of three unequal angles. Each princi- 
pal axis unites two opposite regular edges. This form is 

, . . . 00 0^1 

derived from the tetrakishexahedron, and its sign is — - — , 
one of the most common varieties being — - — , found fre- 
quently in iron pyrites and cobaltine. (2.) The dyakisdo- 



FORM OF MINERALS. 31 

decahedron • (fig. 13), bounded by twenty-four trapezoids 
with two sides equal, has twelve short, twelve long, and 
tAventy-four intermediate edges. The angles are six equi- 
angular rhombic, united in pairs by the pirincipal axes, eight 
trigonal, and twenty-four irregular tetragonal angles. It is 

— , I 

the brackets being used to distinguish it from the hexakiste-. 



Fig. 14. Fig. 15. 

trahedron, also derived from the same primary form. It 
occurs in iron pyrites and cobaltine. There are two other 
tetrahedral forms, the pentagonal dodecahedron (fig. 14), 
and the pentagonal icositetrahedron (fig. 15), both bounded 
by irregular pentagons, but not yet observed in nature. 

Combinations. — These forms of the tesseral system (and 
this is true also of the five other systems of crystallization) 
not only occur singly, but often two, three, or more are united 
in the same crystal, forming Tvhat are named combinations. 
In this case it is evident that no one of the individual forms 
can be completely developed, because the faces of one form 
must partially interfere with the faces of the other forms. 
A combination therefore implies that the faces of one form 
shall appear symmetrically disposed between the faces of 
other forms, and consequently in the room of certain of 
their edges and angles. These edges and angles are thus, 



32 



A PRACTICAL TKEATISE ON GEMS. 



as it were, cut off, and new ones produced in their place, 
which properly belong neither to the one form nor the other, 
but are edges or angles of combination. Usually, one form 
predominates more than the others, or has more influence on 
the general aspect of the crystal, and hence is distinguished 
as the predominant form, the others being named subordi- 
nate. The following terms used on this subject require ex- 
planation. A combmation is developed when all the forms 
contributing to its formation are pointed out ; and its sign 
consists of the signs of these forms, written in the order of 
their influence on the combination, with a point between. 
An angle or edge is said to be replaced when it is cut off 
by one or more secondary planes ; it is truncated when cut 
by one plane, forming equal angles with the adjacent faces ; 
and an edge is bevelled when"replaced by two planes, which 
are equally inclined to the adjacent faces. 

It will be readily seen that such combinations may be 
exceedingly numerous, or rather infinite ; and only a few 
of the more common can be noticed, simply as specimens 
of the class. Many others more complicated will occur in 
the descriptive part of this treatise. Among plenotesseral 
combinations, the cube, octahedron, and also the rhombic- 
dodecahedron, are the predominant forms. In fig. 16 the 






Fig. la 



Fig. IT. 



cube has its angles replaced by the faces of the octahedron, 
and the sign of this combination is ooOoo .0. In fig. 17 
this process may be regarded as having proceeded still fur- 



FORM OP MINERALS. 



33 



ther, so that the faces of the octahedron now predominate, 
and the sign, of the same two elements but in reverse order, 
is O . ooOoo. In fig. 18 the cube has its edgesre placed 





Fiff. 18. 



Fig. 19. 



by the faces of the rhombic-dodecahedron, the sign being 
00 O 00 . 00 O ; while in fig. 1 9 there is the same combina- 
tion, but with the faces of the cube subordinate, and hence 
the symbol is coO . ooOoo . The former figure, it will -be 
seen, has more the general aspect of the cube ; the latter of 
the dodecahedron. 

In combinations of semitesseral forms with oblique faces, 
the tetahedron, the rhombic-dodecahedron, or even the 
hexahedron, seldomer a trigonal-dodecahedron, are the more 





Fig. 20. 



Fig. 21. 



common predominant forms. In fig. 20 two tetrahedrons 

in opposite positions, — .• — — , are combined. In fig. 21 a 

2* 



34 



A PRACTICAL TREATISE ON GEMS. 



very comi^lex combination of seven forms is represented in 
a crystal of gray-copper ore, its full sign being — 

If {I') . coOoo (/) . ooO(o).^(P).-^«.^K) . »03(.); 

the letters in brackets connecting them with the respective 
faces of the figure. As examples of combinations of semi- 
tesseral forms with parallel faces, we may take fig. 22, in 





Fig. 22. 



Fis. 23. 



which each of the angles of the cube is unsymmetrically 
replaced by three faces of the dyakisdodecahedron, and 

^ I ; or fig. 23, in which the pentagonal- 
dodecahedron has its trigonal angles replaced by the faces 

00O2 
of the octahedron, consequently with the sign . O. 

Figure 24 represents the same com- 
bination but with greater predomi- 
nance of the faces of the octahedron, 
the crystal being bounded by eight 
equilateral and twelve isosceles tri- 
angles. 

II. Tetragonal System. — This sys- 
tem has three axes at right angles, 
two of them equal'and one unequal. The last is the princi- 
pal axis, and when it is brought into a vertical position the 
crystal is said to be placed upright. Its ends are named 




Fig. 24. 



FOEM OF MINERALS. 35 

poles, and the edges connected with them polar edges. The 
two other axes are named subordinate or lateral axes, and 
a plane passing through them is named the basis of the 
crystal. ' The two planes that pass through the principal 
and one of the lateral axes are named normal chief sections, 
and a plane through the chief axis intermediate to them, a 
diagonal chief section. The name tetragonal is derived 
from -tlie form of the basis, which is usually quadratic. 

There are eight tetragonal forms, of which five are closed^ 
— ^that is, bounded on all sides by planes, and of. definite 
extent, — and three open., which in certain directions are not 
bounded, and consequently of indefinite extent. 

The description of the varieties is as follows, it being 
premised that a crystallographic pyramid is equivalent to 
two geometrical pyramids joined base to base. 



Fig. 25. Fig. 26. 

Closed forms. — (1.) Tetragonal pyramids (figs. 25, 26) are 
inclosed by eight isosceles triangles,- w4th four middle edges 
all in one plane, and eight polar edges. There are three 
kinds of this form, distinguished by the position of the lat- 
eral axes. In the first these axes unite the opposite angles ; 
in the second they intersect the middle edges equally; 



36 



A PEACTICAL TREATISE ON GEMS. 



and in the third they lie in an intermediate position, or 
divide these edges unequally ; the latter being hemihedral 
forms. These pyramids ar^ also distinguished ' as obtuse 
(fig. 25) or acute (fig. 26), according as the vertical angle 
is greater or less than in the octahedron, which, though 
intermediate, is never a tetragonal form. (2.) Ditetragonal 
pyramids (fig. 27) are bounded by sixteen scalene triangles, 





Fiff. 27. 



Fig. 28. 



whose base lines are all in one plane. This form rarely 
occurs except in combinations. (3.) Tetragonal sphenoids 
(fig. 28), bounded by four isosceles triangles, are the hemi- 
hedral forms of the first variety of tetragonal pyramids. 
(4.) The tetragonal scalenohedron (fig. 29), bounded by 
eight scalene triangles, whose bases rise and fall in a zig-zag 
line, is the hemihedral form of the ditetragonal pyramid. 
The latter two forms are rare. 

Open forms. — Tetragonal prisms (fig. 30) bounded by 
four planes parallel to the principal axis; ditetragonal 
prisms by eight similar planes. In these prisms the. prin- 
cipal axis is supposed to be prolonged infinitely, or to be 
unbounded. Where it is very short and the lateral axes 



FORM OF MINERALS. 



37 



infinite, the basal pinacoid is formed, consisting merely ot 
two parallel faces. • 

The various series of tetragonal crystals are distinguished 
from each other only by their relative dimensions. To- 




Fi&29. 



Fig. 80. 



determine these, one of the series must be chosen as the 
fundamental form, and for this purpose a tetragonal pyramid 
of the first variety, designated by P as its sign, is selected. 
The angle of one of its edges, especially the middle edge, 
found by measurement, determines its angular dimensions ; 
while the proportion of the principal axis (a) to the lateral 
axes supposed equal to 1, gives its linear dimensions. The 
parameter, therefore, of each face of the fundamental form 
are 1 : 1 : a. 

Now if m be any (rational) number, either less or greater 
than 1, and if from, any distance ma m the principal axis 
planes be drawn to the middle edge of P, then new tetra- 
gonal pyramids of the first kind, but more or less acute or 
obtuse than P, are formed. The general sign of these 
pyramids is mP, and the most common varieties ^P, 2P, 
3P; with the chief axis equal to^, twice or thrice that of 
P. If m becomes infinite, or = oo, then the pyramid passes 
into a prism, indefinitely extended along, the principal axis, 



38 



A PKACTICAL TREATISE ON GEMS. 



and with the sign ooP; if m=0, which is the case when 
the lateral axes are supposed infinite, then it becomes a 
pinacoid, consisting properly of two basal faces, open to- 
-wards the lateral axes, and designated by the sign OP. The 
ditetragonal pyramids are produced by taking in each lateral 
axis distances n greater than 1, and drawing two planes to 
these points from each of the intermediate polar edges. 
The parameters of these planes are therefore m : 1 ; w, and 
the general sign of the form mPn, the most common values 
o1l n being |, 2, 3, and oo. When w = oo, a tetragonal, 
pyramid of the second kind arises, designated generally by 
mP 00, the most common in the mineral kingdom being P oo 
and 2P00. The relation of these to pyramids .of the first 





Fig. 31. 



Fig. 32. 



kind is shown in fig. 31, where ABBBX is the first, and 
ACCCX the second kind of pyramid. In like manner from 
the prism 00 P, the ditetragonal prisms ccVn are derived, 
and finally when 71 = cc^ the tetragonal prism of the sec- 
ond kind, whose sign is 00 Poo . ' 

The combinations of the tetragonal system are either 
holohedric or hemihedric ; but the latter are rare. Prisms 
and pinacoids must always be terminated on the 023en sides 
by other forms. Thus in fig. 32 a square prism of the first 
kind is terminated by the primary pyramid, and has its 



FORM OF MINERALS. 



39 



lateral angles again replaced by another more acute pyra- 
mid of the second kind, so that its sign. is ooP . P . 2Pco. 
In fig. 33 a prism of the second kind is first bounded by 






Fig. 34. 

the fundamental pyramid, and then has its edges of combi- 
nation replaced by a ditetragonal 
pyramid, and its sign is here 
ooPoo . P . 3P3.' In fig. 34 the 
polar edges of the pyramid are 
replaced by another pyramid, its 
sign being P. Poo . In fig. 35 a 
hemihedric form very characteris- 
tic of copper pyrites is represented, 
P and P' being the two sphenoids, 
a the basal pinacoid, and 5," c, two ditetragonl pyramids. 

III. The Hexago7ial System. — The essential character of 
this system is, that it has four axes, — three equal lateral axes 
intersecting each other in one plane at 60°, and one principal 
axis at right angles to them. The extremities of the prin- 
cipal axis are named poles, and sections through it and one 
lateral axis, normal chief sections. The plane through the 
lateral axes is the basis, and from its hexagonal form gives 
the name to the system. As in the last system, its forms 
are either closed or open / and are divided into holohedral, 



Fis. 35. 



40 



A PKACTICAL TREATISE ON GEMS. 



hemihedral, and tetartohedral,^the last forms with only a 
fourth i^art of their faces developed. The tetartohedral and 
many of the hemihedral forms are of rare occurrence, and 
only a few of the more common require to be here described. 
The hexagonal pyramids (figs. 36, 37) are bounded by 
twelve isosceles triangles, and are of three kinds, according 





Fig. 36. 



Fig. 87. 



as the lateral axes fall in the angles, in the middle of the 
lateral edges, or in another point of these edges, the latter 
being hemihedral forms. They are also classed as acute 
or obtuse, but without any very precise limits. The trigo- 
nal pyramid is bounded by six triangles, and may be viewed 
as the hemihedral form of the hexagonal. The dihexago- 
nal pyramid is bounded by twenty-four scalene triangles, 
but has never been observed alone, and rarely even in com- 
binations. The more common prisms are the hexagonal of 
six sides, and the dihexagonal of twelve sides. 

As the fundamental form of this system, a particular pyr- 
amid P is chosen, and its dimensions determined either 
from the proportion of the lateral to the principal axis 
(1 : a), or from the measurement of its angles. From this 
form (mP) others are derived exactly as in the tetragonal 



FOEM OF MINERALS. 



41 



system. Thus dihexagonal pyramids are produced with 
the general sign mPn, the chief pecuharity being that, 
whereas in the tetragonal system n might have any rational 
value from 1 to oo, in the hexagonal system it can only 
vary from 1 to 2, in consequence of the geometric charac- 
ter of the figure. When ^=2 the dihexagonal changes 
into an hexagonal pyramid of the second kind, whose sign 
is mP2. When m is = oo various prisms arise from similar 
changes in the value of n ; and when m=0, the basal pina- 
coid. 

Few hexagonal mineral species form perfect holohedric 
combinations. Though quartz and apatite appear as such, 





Fig. 38. 



Fig. 39. 



yet properly the former is atetartohedral, the latter a hem- 
ihedral species. In holohedric species the predominant 
faces are usually those of the two hexagonal prisms coP 
and 00 P2, or of the pinacoid OP; while the pyramids P 
and 2P2 are the most common subordinate forms. Figure 
38 represents the prism, bounded on the extremities by two 
pyramids ; one, P, forming the point, the other 2P2, the 
rhombic faces on the angles, or ooP . P . 2P2. In some 
crystals the lateral edges of the prism are replaced by the 



42 A PEACTICAL TREATISE ON GEMS. 

second prism 00P2, producing an equiangular twelve-sided 
prism, which always represents the combination 00 P. 00 P2, 
and cannot occur as a simple form. An example of a more 
complicated combination is seen in fig. 39, of a crystal 
of apatite, whose sign with the corresponding letters is 
ooP(3jr) . ooP2(e) . OP(P) . AP.(r) . P(a;) . 2P(2) . P2(a) . 
2P2(s) . 4P2(^). 

Hexagonal minerals more frequently crystallize in those 
series of hemihedral forms that are named rhombohedral, 
from the prevalence in them of rhombohedrons. These 
are bounded by six rhombs (fig. 40), whose lateral edges do 





Fig. 40. 

not lie in one plane, but rise and fall in a zig-zag manner. 
The principal axis unites the two trigonal angles, formed by 
three equal plane angles, and in the most common variety 
the secondary axes join the middle points of two opj^osite 
edges. When the polar edges form an angle of more than 
90°, the rhombohedrons are named obtuse ; when of less, 
acute. Hexagonal scalenohedrons (fig. 41) are bounded 
by twelve scalene triangles, whose lateral edges do not lie 
in one plane. The principal axis joins the two hexagonal 
angles, and the secondary axes the middle points of two 
opposite lateral edges. 

The rhombohedron is derived from the first kind of 
hexagonal pyramid by the hemihedric development of its 

alternate faces. Its general sign should therefore be -— ; 



FORM OP MINERALS. 



43 



but on several grounds it is found better to designate it by 
R or mR, and its complimentary figure by — mR. When 
the prism or pinacoid arise as its limiting forms, they are 
designated by ooR and OR, though in no respect changed 
from the limiting forms ooP and OP of the pyramid. The 
scalenohedron is properly the hemihedric form of the 
dihexagonal pyramid, but is better derived from the 
inscribed rhombohedron ttiR. If the halves of the prin- 
cipal axis of this are multiplied by a definite number n. 





Fig. 41. 

and then planes drawn from the extremities of this enlarged 
axis to the lateral edges of the rhombohedron, as in figure 
42, the scalenohedron is constructed. Hence it is desig- 
nated by mR", the n being written on the right hand, like 
an algebraic exponent : and the dihexagonal prism is in 
like manner designated by ooR". 



44 



A PEACTICAL TREATISE OX GEMS. 



The combinations of rhombohediic forms are very nu- 
merous, some hundreds being described in calc-spar alone. 
Among the more common is the prism in combination with 
a rhombohedron, as in the twin crystal of calc-spar (fig. 43), 



rr— f -:, 




Fig. 43, 



Fig. 44. 



with the sign ooR, — iR, the lower half being the same 
form with the upper, but turned round 180°. In figure 
44, the rhombohedron mR has its polar edges replaced by 




Fig. 45. 




Fiar. 46. 



another rhombohedron — JwR ; and in figure 45 its lateral 
edges bevelled by the scalenohedron mR". A more com- 



FORM OF MINERALS. 45 

plex combination of five forms is represented in the crystal 
of calc-spar, fig. 46, its sign with the letters on the faces 
being Il*(y) . R'{r) . R(P) . 4R(m) . oo R(c). Tetartohedric 
combinations are seen most distinctly in pure quartz or rock- 
crystal, the pyramids of the first kind appearing as rhom- 
bohedrons, those of the second kind as trigonal pyramids, 
the dihexahedral prisms as ditrigonal prisms, and the prism 
00P2 as a trigonal prism. Most of these forms, however, 
occupy but a very subordinate place in the combinations 
\Vhich consist essentially of the prism 00 P, and the rhom- 

P 

bohedron R, = — . 
4. 

lY. Hhomhic System. — The rhombic system is charac- 
terized by three axes, all unequal, but at right angles to 
each other. One of these is assumed as the chief axis, 
when the others are named subordinate. The plane pass- 
ing through the secondary axes, or the basis, forms a 
rhomb, and from this the name is derived. This system 
comprises only a few varieties of forms that are essentially 
distinct, and its relations are consequently very simple. 



Fig. 4T. Fig. 48. 



The closed forms . are, — {Ist) The rhombic pyramids 
(figs. 47, 48), bounded by eight scalene triangles, whose 



46 



A POPULAR TREATISE ON GEMS. 




Fig. 49. 



lateral edges lie in one plane, and form a rhomb. They 

have eight polar edges, — four acute and four more obtuse, 

— and four lateral edges, and six rhombic angles, the most 

•acute at the extremities of the longest axis. {2d.) The 

rhombic sphenoids (fig. 49) 

are bounded by four scalene 

triangles with then- lateral 

edges not in one plane ; 

and are a hemihediic form 

of the rhombic pyramid of 

unfrequent occurrence. The 

open forms again are, — (dd.) 

Rhombic prisms bounded 

by four j^lanes parallel to 

one of the axes which is 

indefinitely extended. They are divided into upright and 

horizontal- prisms, according as either the principal or one of 

the lateral axes is supposed to become infinite. For the 

latter form the name doma or dome has been used ; and 

two kinds, the macrodome and the brachydome, have been 

distinguished. Rhombic pinacoids also arise when one axis 

becomes =0, and the two others are indefinitely extended. 

In deriving these forms from a primary, a particular 
rhombic pyramid P is chosen, and its dimensions determined 
either from the angular measurement of two of its edges, 
or by the linear proportion of its axes a: b: c; the greater 
lateral axis b being assumed equal to 1. To the greater 
lateral axis the name macrodiagonal is frequently given ; 
to the shorter, that of brachydiagonal ; and the two princi- 
pal sections are in like manner named macrodiagonal and 
brachydiagonal, according to the axis they intersect. The 
same terms are applied throughout all the derived forms, 
where they consequently mark only the position of the 
faces in respect to the axes of the fundamental crystal, 



FOEM OF MINERALS. 



47 



without reference to the relative magnitude of the derived 
axes. • 

By multiplying the principal axis by any rational num- 
ber m^ greater or less than 1, a series of pyramids, arise, 
whose general* sign is nri^^ and their limits the prism and 
pinacoid, the whole series being contained in this formula, 

OP ??zP P mP - ooP ; which is 

the fundamental series, the lateral -axes always remaining 
unchanged. From 
each member- a new 
series may, however, 
be developed in twD 
directions by increas- 
ing one or other 
of the lateral axes. 
When the macrodia- 
gonal is thus multi- 
plied by any number 
n greater than 1, and 
planes drawn from 
the distance n to the 
polar edges, a new 
pyramid is produced, 
named a macropyra- 
mid, with the sign 
??iP7^,, the mark over 
the P pointing out 
the axis enlarged. 
When n=oo a ma- 
crodome results, with 

the sign mPco . If the shorter axis is multiphed, then bra- 
chypyramids and brachydomes are produced with' the signs 
mP/i and mPoo . So also from the prism coP, on the one 
side, numerous macroprisms ooP^i, with the limiting ma- 




Fig. 50. 




Fig. 51. 



48 



A POPULAR TREATISE ON GEMS. 



cropinacoid ooPoo ; on the other, numerous brachyprisms 
coP?2, with the Umit form ooPoo, or the brachypinacoid. 
In figs. 50, 51, the two domes are shown in their relation 
to the primitive pyramid. 

The pyramids seldom occur independent, or even as the 
predominant forms in a combination, — sulphur, however, 
being an exception. Prisms or pinacoids usually give the 
general character to the crystal, which then appears either 
in a columnar or tabular, or even in a rectangular pyramidal 
form. The determination of the position of these crystals. 




M 







Flg.SS. 



Fig. 54. 



as vertical or horizontal, depends on the choice of the chief 
axis of the fundamental form. In the topaz crystal (fig. 52) 
the brachyprism and the pyramid are the predominant ele- 
ments, associated with the prism, its sign and letters being 
00 P2(^) . P(o) . ooP(m). Fig. 53 of stilbite is another ex- 
ample, the macropinacoid coPoo or Jf, being combined with 
the pyramid P(r), the brachypinacoid ooPoo (J'), and the 
basal pinacoid OP (P). Another instance is fig. 54 of a 
lievrite crystal, where the brachyprism "and pyramid com- 
bine with the macrodome, or ooP2 ; P . Poo . The follow- 
ing figures are very common forms of barytes; figs. 55 and 



FOEM OF MINERALS. 



^0 



56 being both composed of the pinacoid, a brachydome, and 
macro dome, with sign OP 
(c).Pa,(/) iPc^(^),the 
variation in aspect arising 
from the predominance of 
different faces ; and fig. 5 7 
consisting of the macro- 
dome ^P 



00 




^'^f 





^^\ 


/--■"T" 


d 


\J^ 


V.-r— - 


_ 


..j.^^-^ 



Fig. 58. 





Fig. 57. 



the prism 
00 P(^), and the pinacoid 
OP. 

V. The MonoclinoJie- 
dric System. — This system 
is characterized by three 
mieqnal axes, two of which 
intersect each other at an 
oblique angle, and are cut 
by the third at right an- 
gles. One of the oblique 
axes is chosen as the chief axis, and the other axes are then 
distinguished' as the orthodiagonal (right-angled) and clino- 
diagonal (oblique-angled). The same terms are applied to 
the chief sections, and the name of the system refers to the 
fact that these two planes and the base, together with two 
right angles, form also one oblique angle C. 

The forms of this system approach very near to those of 
the rhombic series, but the inclination of the axes, even 
when almost a right angle, gives them a peculiar character, 
by which they are always readily distinguished. Each 
pyramid thus separates into two altogether ^independent 
forms or hemipyramids. Three varieties of prism also oc- 
cur, — vertical, inclined, and horizontal, — with faces parallel 
to the chief axis, the clinodiagonal or the orthodiagonal. 
The horizontal prisms, like the pyramids, separate into two 
independent partial forms, named hemiprisms or hemi- 



50 



A POPULAR TREATISE ON GEMS. 



S. C 



domes. The inclined prisms are often designated clino- 
domes, the term prism being restricted to the vertical 
forms. Orthopinacoids and clinopinacoids are also distin- 
guished from their position in relation to the axes. 

The monoclinoiiedric pyramids (iig. 58) are bounded by 
A eight scalene triangles of two 

kinds, four and four only be- 
ing similar. Their lateral 
edges lie all in one plane, 
and the similar triangles are 
placed in pairs on the clino- 
diagonal polar edges. The 
two pairs in the acute angle 
between the orthodiagonal 
and basal section are desig- 
nated the positive hemipyra- 
mid ; while the two pairs in 
the obtuse angles of the same 
sections form together the negative hemipyramid. But as 
these hemipyramids are wholly independent of each other, 
they are rarely observed combined. More frequently each 
occurs alone, and then forms a prism-like figure, with faces 
parallel to the polar edges, and open at the extremities. 
Hence, like all prisms, they can only appear in combination 
with other forms. The vertical prisms are bounded by 
four equal faces parallel to the principal axis, and the cross 
section is a rhomb ; the clinodomes have a similar form 
and section; while the horizontal prisms or domes have 
unequal faces, and their section is a rhomboid. 

The mode of derivation of these forms closely resembles 
that of the rhombic series. A complete pyramid is as- 
sumed as the fundamental form, and designated db P, in 
order to express the two portions of which it consists. Its 
dimensions are given when the proportion of its axes a\h\c^ 




FOEM OF MINEEALS. 



51 



and the angular inclination of the oblique axes (7, wliicli is 
also that of the orthodiagonal section to the basis, are 

known. The fundamental series of forms is OP 

=tmP ±P d=mP ooP; from each of 

whose members, by changing the dimensions of the other 
axes, new forms may be again derived. Thus from daniP, 
by multiplying the orthodiagonal by any number n^ a series 
of orthopyramids =fcmP/z, is produced with the orthodomes 
=i=w^Poo , as limiting forms. The clinodiagonal produces a 
similar series, distinguished from the former by the sign 
being put in brackets, thus, ±(mP??.), with the limiting 
clinodome ( mPoo ) always completely formed, and therefore 
without the signs rt attached. From ooP arise ortho- 
prisms ooP;^, and the orthopinacoid ooPoo ; and clino- 
prisms (ooP^), and the clinopinacoid (ooPoo). 

The combinations of this system may be easily imder- 
stood from their resemblance to those of the rhombic ; the 
chief difficulty being in the occurrence of partial forms, 
which, hoAvever, closely resemble the hemihedric forms of 
the previous systerps. We shall therefore only select a few 
examples frequently observed in the mineral kingdom. 
Fig. 59 represents a very common form of gypsum crystals 





Fig. 59. 

(odPoo) (P) . ooP(/) .P(&). 
augite is represented in fig. 



Fig. 60. 

The most common form of 
60, with the sign ooP(m) . 



52 



A POPULAR TREATISE ON GEMS. 



00 Poo (r) . ( ooPoo ) {I) . P(5). Fig. 61 is a crystal of com- 
mon felspar or orthoclase, composed of the clinopinacoid 
( 00 Poo) (Jf), the prism ooP(7'), the basal pinacoid OP 
(P), and the hemidomes 2Poo (y) : to which, in fig. 62 of 





Fig. 61. 



Fig. 62. 



the same minei^al, the hemipyramid P(o), and the clino- 
dome (2P00) {n)y are added. 

VI. Tricllnohedric System. — This is the least regular of 
all the systems, and departs the most widely from symmetry 
of form. The axes are all unequal, and- inclined at angles 
none of which are right angles, so that to determine any 
crystal or series of forms the proportion of the axes a:h:Cy 
and also their angles, or those of the inclination of the chief 
sections, must be known. As in the previous system, one 
axis is chosen as the principal axis, and the two others dis- 
tinguished as the macrodiagonal and brachydiagonal axes. 
In consequence of the oblique position of the principal sec- 
tions, this system consists entirely of partial forms wholly 
independent on each other, and each composed only of two 
parallel faces. The complete pyramid is. thus broken up 
into four distinct quarter pyramids, and the prism into two* 
hemiprisms. Each of these partial forms is thus nothing 
more than a pair of parallel planes, and the various forms 
consequently mere individual faces. This circumstance 



FOEM OF MINERALS. 



53 



renders many triclinohedric crystals very unsymmetrical in 
appearance. • 

Triclinohedric pyramids (fig. 63) 
are bounded by eight triangles, whose 
lateral edges lie in one plane. They 
are equal and parallel two and two 
to each other ; each pair forming, as 
just stated, a tetartopyramid or open 
form, only limited by combination 
with other forms, or, as we may sup- 
pose, by the chief sections. The 
prisms are again either vertical or in- 
clined ; the latter named domes, and 
their section is always rhomboidal. In deriving the forms, 
the fundamental pyramid is placed upright with its brachy- 
diagonal axis to the spectator, and the partial forms desig- 
nated, the two upper by 'P and P', the two lower by ^P 
and P^, as in the figure. The fiirther derivation now follows 
as in the rhombic system, with the modifications already 
mentioned, so that we need not delay on it longer, especially 
as the minerals crystallizing in these'forms are not numerous. 




Fiff. 63. 




Fig. 64. 



Some combinations of this system, as the series exhibited 
by most of the felspars, approach very near to the mono- 
clinohedric system ; while others, as the blue copper, or 



54 



A POPULAR TREATISE ON GEMS. 



vitriol, and axinite, show great incompleteness and want of 
symmetry. In the latter case the determination of the 
forms is often difficult and requires great attention. As 
specimens, we may notice the albite crystal (fig. 64), in 
which P is the basal pinacoid OP; ilTthe brachydiagonal 
pinacoid ooPoo ; s the uppier right pyramid P' ; Ztbe right 
liemiprism ooP' ; 2^ the left hemiprism oo'P; and x the 
hemidome 'P'oo . Figures 65 'and 66 are crystals of axinite. 





Fia:. 65. 



Fig. 66. 



the former from Dauphine, the latter very common in Cora- 
wall, of whose faces the following is the development : — r 
the macropinacoid ooPoo; P the left hemiprism oo'P; i/ 
the left upper quarter pyramid 'P ; I the left upper quarter 
pyramid 2T; s the left upper partial form of the macro- 
pyramid 3'P3 ; and x the hemidome 2'P^oo . 

Imperfections of Crystals. 

In the foregoing description of the forms of crystals the 
planes have been supposed smooth and even, the faces 
equal and uniform, or at the same distance from the centre 
or point of intersection of the axes, and each crystal also 
perfect or fully formed and complete on every side. In 
nature, however, these conditions are rarely if ever real- 
ized, and the edges of crystals are seldom straight lines, or 
the faces mathematical plane surfaces. A very interesting 
vari^y of these irregularities, which pervades all the sys- 
tems except the tesseral, is named hemimorphism. In this 



FOKM OF MINERALS. 



55 



the crystals are bounded on the opposite ends of their chief 
axis by faces belonging to distinct forms, and hence only 
the upper or under half of each form is produced, or the 
crystal, as the name implies, is half formed. Figure 67 rep- 
resents a common variety of tourmaline, bounded on the 






Ficf. 67. 



Fig. 68. 



upper end by the planes of the rhonibohedrons E. and— 2R, 
and on^the lower end by the basal pinacoid. In fig. 68 of 
electric calamine the upper extremity shows the basis ^, 
two brachydomes o and p^ and two macrodomes m and ^; 
while on the lower end it is bounded by the faces P of the 
primary form. This appearance becomes more interesting 
from the fact that most hemimorphic crystals acquire polar 
electricity from heat, — that is, exhibit opposite kinds of 
electricity at opposite ends of the crystal. 

The faces of crystals are very frequently rendered im- 
perfect by stride^ or minute linear and parallel elevations 
and depressions. These arise in the oscillatory combination 
of two crystal forms, alternately prevailing through small 
spaces. The strige, therefore, are in reality the edges of 
combined forms. They are very common on quartz, shorl, 
and some other minerals ; and frequently indicate combina- 
tions where only a simple form would otherwise appear* to 
exist. The cubes and pentagonal dodecahedrons of iron 



56 A POPULAR TREATISE O^ GEMS. 

pyrites are frequently striated, and in three directions at 
right angles to each other. In calc-spar the faces of the 
rhombohedron, — ^R (^ in fig. 43 above) are almost never 
without striae parallel to the oblique diagonal. The stria- 
tion is said to be simple when only one series of parallel 
lines appears on each face, or feathered when two systems 
diverge from a common line. In other crystals the faces, 
then said to be drusy^ are covered by numerous projecting 
angles of smaller crystals; an imperfection often seen in 
fluor spar. The faces of crystals occasionally appear curved 
either, as in tourmaline and beryl, from the peculiar oscil- 
latory combination mentioned, or by the union of several 
crystals at obtuse angles, like stones in a vault, as in stilbite 
and prehnite. A true curvature of the faces probably oc- 
curs in the saddle-shaped rhombohedrons of brown sj^ar 
and siderite, in the lens-Hke crystals of gypsum, and in the 
curved faces so common on diamond crystals. In chabasite 
similar curved faces occur, but concave. In galena and 
augite the crystals are often rounded on the corners, as if by 
an incipient state of fusion. On other crystals the faces are 
rendered uneven from inequalities following no certain rule. 
These imperfections furnish valuable assistance in develop- 
ing very complex combinations, all the faces of each indi- 
vidual form being distinguished by the same peculiarity of 
surface. 

LTegularities in the forms of crystals are produced when 
the corresponding faces are placed at unequal distances 
fi*om the centre, and consequently differ in form and size. 
Thus the cubes and octahedrons of iron pyrites, galena, and 
fluor spar, are often lengthened along one axis. Quartz is 
subject to many such irregularities, which are seen in a very 
remarkable manner on the beautiful transparent and sharply 
angular crystals from Dauphine. In such irregular forms, 
instead of one line, the axes are then represented by an 



FOEM OF MINERALS. 57 

infinite number of lines, parallel to the ideal axis of the 
figure. The same irregularity carried to a greater extent 
frequently causes certain faces required for the symmetry 
of the form, altogether to disappear. Again, some crystals 
do not fill the space marked out by their outline, holes and 
vacancies being left in the faces, occasionally to such an 
extent that thej seem little more than mere skeletons. 
This appearance is very common on crystals produced ar- 
tificially, as in common salt, alum, bismuth, silver, &c. A 
perfect crystal can only be produced when, during its for- 
mation, it is completely isolated, so as to have full room to 
expand on every side. Hence the most perfect crystals 
have been originally imbedded singly in some uniform rock 
mass. Next to them in perfection are forms that grow 
singly on the surface of some mass of similar or distinct 
composition, especially when the point of adherence is 
small. An incompleteness of form, or at least a difficulty 
in determining it, arises from the minuteness of some crys- 
tals, or from their contracted dimensions in certain direc- 
tions. Thus some appear mere tabular or lamellar planes, 
while others run out into acicular, needle-shaped, or capil- 
lary crystals. Amid all these modifications of the general 
form of the crystal, of the condition and aspect of its indi- 
vidual faces, or of its linear dimensions, one important ele- 
ment, the angular measurement, remains constant. In some 
monoaxial crystals, indeed, increase of temperature produces 
an unequal expansion in different directions, slightly chang- 
ing the relative inclination of the faces, but so small as to 
be scarcely perceptible in common measurements, and hence 
producing no ambiguity. More important are the angular 
changes which in many species accompany slight changes 
in chemical composition, particularly in the relative propor- 
tions of certain isomorphous elements. But notwithstand- 
ing these limitations, the great truth of the permanence of 

3* 



58 



A POPULAR TREATISE ON GEMS. 



the angular dimensions of crystals, announced by Rome de 
I'Isle, remains unaffected; only, as Mohs well states, it 
must not be interpreted with a rigid immutability, incon- 
sistent with the whole analogy of other parts of nature. 



The Goniometer and Measurement of Crystals. 

The fact just stated of the permanence of the angular di- 
mensions of crystals, shows the importance of some accurate 
method of measuring their angles ; that is, the inclination 
of two faces to each other. 
Two instruments have been 
specially used for this pur- 
pose, — the common or contact 
goniometer, invented by Ca- 
ringeau, and the reflecting go- 
niometer of Wollaston. The 
former is simply two brass 
rulers turning on a common 
centre, between 



which the 
crystal is so placed that its 
faces coincide with the edges 
of the rulers, and the angle is 
then measured on a graduated 
arc. This instrument is suffi- 
ciently accurate for many pur- 
poses and for large crystals ; 
but for precise determination 
is far inferior to the reflecting 
goniometer. This requires 
smooth and even faces, but 
these may be very small, even 
the hundredth of an inch, in skilful hands ; and as small 
crystals are generally most perfect, far greater accuracy can 




Fig. 6i). 



FOEM OF MINERALS. 59 

be attained, and the measurement depended on to one 
m.imite (1'). 

The reflecting goniometer is represented in fig. 69. It 
consists essentially of a graduated circle mm, divided on its 
edge into twice 180°, or more often into half degrees, the 
minutes being read off by the vernier hh. This circle turns 
on an axis connected with t% so that by turning this the 
circle is moved round, but is stopped at 1 80°, when moving 
in one direction, by a spring at h. The other part of the 
instrument is intended to attach and adjust the crystal to 
be measured. The first axis of mtn is hollow, and a second 
axis, aa, passes through it from 55, so that this and all the 
connected parts from h to f can -be turned without moving 
the circle mm. The axis d passes through a hole in he, so 
that it can turn the arm de into any required position ; f is 
a similar axis. turning the arm og; and pq a fourth axis, in 
like manner movable in g, and with a small knob at q, to 
which the crystal to be measured is attached. 
" When about to use the instrument, it should be placed 
on a table, with its base horizontal, which is readily done 
by the screws in it, and opposite to a window at about 12 
or 15 feet distance, so that its axis shall be parallel to the 
horizontal bars of the window. One of the upper bars of 
the window, and also the lower bar, or, instead of the lat- 
ter, a white line on the floor or table parallel to the window, 
should then be chosen in order to adjust the crystal. The 
observer places himself behind the instrument with the side 
a at his right hand. The crystal is then attached to q by 
a piece of wax, with the two faces to be measured upward. 
The axis fo is made parallel to aa, and the eye being 
brought near to the first face of the crystal, the axes aa 
and p are turned till the image of the window is seen re- 
flected in the face with the horizontal and vertical bars in 
their position. The axis d is then turned through a con- 



60 A POPULAR TKEATISE ON GEMS. 

siderable angle (say 60°), and the image of the window 
again sought and brought into its proper place by turning 
the axis/", without moving^:?. When this is done, that face 
is brought into its true jDosition, normal to c?, so that no 
motion of d can disarrange it. Hence the image of the 
window may now be sought in the second face and brought 
into its true position, with the horizontal bars seen horizon- 
tal, by moving the axes d and a. When this is done the 
crystal is properly adjusted, and the angle is thus measured. 
First bring the zero of the circle and vernier to coincide, 
and then turn the inner axis a or S5, and move the eye till 
the image of the upper bar of the window reflected from 
the more distant face of the crystal coincides with the lower 
bar or horizontal line seen directly. Keeping the eye in 
its place, turn the outer axis tt till the reflected image of 
the upper bar in the other face in like manner coincides 
with the lower line, and the angle of the two faces is then 
read ofl* on the divided circle. As the angle measured is 
not directly that of the faces, but of the rays of light re- 
flected from them, or the difference of the angle wanted 
fi'om 180°, the circle has the degrees numbered in the re- 
verse direction, so as to give the angle without the trouble 
of subtracting the one from the other. 

The above apparatus for adjusting the crystal is an im- 
provement suggested by Naumann. In the original instru- 
ment the axis fo was made to push in or out in a sheath, 
and had a small brass plate, bent at right angles, inserted 
in a cleft at o, to which the crystal was attached. The crys- 
tal was adjusted, as formerly, by moving the plate, or the 
axis/o, and by slight motion of the arm de^ which should 
be at right angles nearly to 5c when used. A considerable 
improvement is, to have a small mirror fixed on the stand 
below the crystal, with its face parallel to the axis «<x, and 
inclined at 45° to the window, when the lower line can be 



FOEM OF MINEKALS. 61 

dispensed with, and the instrument used for various other 
purposes of angular measurement. Many alterations have 
been suggested for the purpose of insuring greater accuracy, 
but the simple instrument is sufficient for all purposes of de- 
terminative mineralogy, and the error from the instrument 
will in most cases be less than the actual variations in the 
dimensions of the crystals. Greater simplicity is indeed 
rather desirable, and the student will often find it sufficient 
to attach the crystal by a piece of wax to the axis a directly, 
and give it the further adjustment by the hand. The only 
use of the parts from 5 to §' is to enable the observer to 
place the crystal properly; that is, with the edge to be 
measured parallel to the axis of the instrument, and as 
nearly as possible coinciding with it^- centre. This is 
effected when the reflection of the horizontal bar in the 
two faces appears parallel to that edge. 

Mades or Twin Crystals. 

When two similar crystals of a mineral species ai'e united 
with their similar faces and axes parallel, the one forma 
merely a continuation or enlargement of the other, and 
every crystal may be regarded as thus built up of a num- 
ber of smaller crystals. Frequently, however, crystals are 
united according to precise laws, though all their similar 
faces and axes are not parallel, and then are named macles 
or twin crystals. In one class of macles the axes of the 
two crystals are parallel, and in another they are inclined. 
The former only occur among hemihedric forms, and the 
two crystals are then combined in the exact position in 
which they would be derived from or reproduce the pri- 
mary holohedric form. The second class, with oblique 
axes, occur both in holohedric and hemihedric forms, and 
the two individuals are placed in perfect symmetry to each 



62 A POPULAR TREATISE ON GEMS. 

Other, in reference to a particular face of the crystal which 
forms the j^lane of union, or the equator of the made. We 
may also suppose the two crystals originally parallel, and 
the one turned round the normal of the united faces by 180° 
(often 90° or 60°), while the other is stationary. Or we 
may suppose a crystal cut into halves in a particular direc- 
tion, and one half turned 180° on the other; and hence the 
name of hemitrope given to them by Hauy. The position 
of the two individuals in this case corresponds with that of 
an object and its image in a mirror, whose surface then 
represents the plane of union. 

The manner in which the crystals unite also differs. 
Some are merely opposed or in simple contact ; others are, 
as it were, grown together, and mutually interpenetrate, 
occasionally so completely as to appear like one individual. 
The twin edges and angles in which the two unite are often 
re-entering ; or they may coincide in one plane, when the 
line of union is either imperceptible, or is only marked by 
the meeting of two systems of striae, or other diversity in 
the physical characters of the two faces. 

The formation of twin crystals may be again repeated, 
forming groups of three, four, or more. When the faces of 
union are parallel to each other, the crystals form rows of 
indeterminate extent ; where they are not parallel, they 
may return into each other in circles, or form bouquet-like 
or other groups. Where crystals are merely in juxtaposi- 
tion, they are sometimes much shortened in the direction 
of the twin axis; and where many occur in a series with 
parallel position, are often compressed into very thin plates, 
frequently not thicker than paper, giving to the surface of 
the aggregate a peculiar striated aspect. 

Only a few twin crystals in the different systems can be 
noticed, chiefly as examples of this mode of formation. In 
the tesseral system, forms that unite with parallel axes pro- 



FORM OF MINERALS. 



63 



duce intersecting macles like the pentagonal dodecahedrons 
of iron pyrites in fig. 70, and the tetrahedrons of gray-cop- 





Fi?. 70. 



Fig. 71. 



per or fahlore in fig. 71, a similar formation also occurring 
in the diamond. In macles with inclined axes the two 
forms almost always unite by a face of the octahedron, and 
the two individuals are then generally apposed and short- 
ened in the direction of the twin axis by one half, so that 
they appear like a crystal that has been divided by a plane 
parallel to one of its faces, and the two halves turned round 
on each other by an angle of 180°. In this manner two 
octahedrons of the spinel, magnetic iron ore, or automolite 





Fig. 72. 



Fig. 73. 



(fig. 72), are frequently united. The same law prevails in 
the intersecting cubes of fluor spar, iron pyrites, and galena, 



64 



A POPULAR TREATISE ON GEMS. 



represented in iig. 73. In fig. 74 of zinc-blende, two rhom- 
bic dodecahedrons are united by a face of the octahedron. 
In the Tetragonal system, twin crystals with parallel axes 





Fig. 74. 



Fie 75. 



rarely occur, but are seen in chalcopyrite, and one or two 
other minerals. Where the axes are inclined the plane of 
union is very often one of the faces of the pyramid Poo , or 
one of those faces that would regularly replace the polar 
edges of the fundamental form P. The crystals of tin ore 
obey this law, as seen in fig. 75, where the individuals are 
pyramidal, and in the knee-shaped crystal (fig. 76), where 




Fig. 76. 




Fig. 77. 



they are more prismatic. Hausmanite appears like fig. 77, 
in which the fundamental pyramid P prevails, on whose polar 
edges other crystals are often very symmetrically repeated. 



POEM OF MINEEAXS. 



65 



a central individual appearing like the support of all the 
others. Almost identical forms occur in chalcopyrite. 

In the Hexagonal system, twin crystals with parallel axes 
are common, as in calc-spar, chabasite, haematite, and other 
rliombohedric minerals. In calc-spar they often form very 
regular crystals, the two individuals uniting by a plane 
parallel to the base, so as to appear like a single crystal, as 
in fig. 78, where each end shows the forms ooR. — | R, but 
in a complementary position ; or in fig. '79 of two seal en o- 
hedrons W from Derbyshire. The rliombohedric crystals 
of chabasite often api5ear intersecting each other, like those 
of fluor spar in fig. 73. The purer varieties of quartz or 



-s^-^^^-^ 





Fig. 78. 



Fig. 79., 



Fig. 80. 



rock crystal, in consequence of the tetartohedric character 
of its crystallization, often exhibit twins. In these the 
pyramid P separates into two rhombohedrons J* and z, 
which, though geometrically similar, are jet physically 
distinct. In fig. 80 the two individuals are only grown to- 
gether, but more commonly they penetrate each other in 
an irregular manner, forming apparently a single crystal. 
Twins with oblique axes are also common, the plane of 
union being usually one face of the rhombohedron. Thus 
in calc-spar two rhombohedrons are often joined by a face 



63 



A POPULAR TREATISJS OX GEMS. 



of— gR, the two axes forming an angle of 12*7° 34'; occa- 
sionally a third individual is interposed in a lamellar form, 
as in fig. 81, when the two outer crystals become parallel. 





Fig. 81. 



Fig. 82. 



This latter arrangement is very common in the highly 
cleavable varieties of Iceland spar. When the crystals 
unite in a face of the rhombohedron R,-fig. 82, they form 
an angle of 89° 8', difiering little from a right angle, by 
which the occurrence of this law is very easily recognized, 
especially in prismatic varieties. 

In the rhombic system, twin crystals with parallel axes 
are very rare, but those with oblique axes common, the 
plane of union being one of the faces of the prism ooP. 
Twins of this kind are very distinctly seen in arragonite, 



/^^W 



M 



M 



:^ 



M 



\M\ 



w 




Fig. 83. Fig. 84, Fig. 85. 

carbonate of lead, marcasite, stephanite, mispickel, and 
other minerals. In arragonite the crystals partly interpen- 



FOEM OF MINEEALS. 



67 



etrate, partly are in mere juxJ;aposition, as in fig. 83, where 
the individuals are formed by the combination qoP(J!/") . 
00 Poo (A), Poo (^), and in figm-e 84 where several crystals 
of the same combination form a series with parallel planes 
of union ; the inner members being so shortened that they 
appear like mere lamellar plates producing striae on the 
faces Poo and ooPoo of the made. In fig. 85 four crystals, 
each of the combination ooP . 2Poo , having united in in- 
clined planes,' form a circular group, returning into itself. 
The carbonate of lead often occurs in macles in all respects 





Fis. SC 



Fisr. ST. 



similar. In staurolite, individuals of the prismatic combi- 

tion GoP . coPco . oP, combine either, as in fig. 86, by a 

face of the brachydome fPoo , with their 

chief axes almost at right angles ; or, as in 

fig. 87, by a face of the brachypyramid 

f P|, the chief axes and the brachypina- 

coids (o) of the two single crystals meeting 

at an angle of about 60°. Finally, in fig. 

88, two harmotome crystals of the most 

common combination ooPoo . ooPoo , P . 

Pgo , intersect each other so nearly at right 

angles, that their principal axes seem to 

coincide, and the brachypinacoid (q) of the one crystal 




68 



A POPULAR TREATISE ON GEMS. 



(with a rhombic striae) is parallel to the macropinacoid (q) 
of the other. 

In the nionoclinohedric system the most common macles 
are those in which the principal axes and the chief sections 
of the two crystals are parallel to each other, and conse- 
quently the principal axis is also the twin axis. Usually 
the two individuals are united by a face parallel to the or- 
thodiagonal chief section, as in figure 89 of gypsum, where 
two crystals of the combination (ooPoo).ooP.— P, shown 
in fig. 59, unite so regularly that the faces of the pinacoids 
(^ and jP') form only one plane. In a similar manner the 
augite crystals of the combination ooP. ooPoo . (ooPoo) . 
P, represented singly in fig. 60, are in fig. 90 united in a 





Fig. 89. 



Fig. 90. 



Fig. 91. 



made so very symmetrical and regular that the line of 
junction cannot be observed on the face of the clinopinacoid. 
The two hemipyramids P (s) (like — P {I) in the gypsum 
crystal above) form on one side a re-entering, on the other 
a salient angle. Hornblende, wolfram," and other minerals 
exhibit a similar appearance. In other cases the individuals 
partially penetrate each other, being, as it were, crushed 
together in the direction of the orthodiagonal. This mode 
of union is not uncommon in gypsum, and very frequent in 
orthoclase felspar. Two crystals of the latter, of the com- 



FORM OF MINERALS. 



69 



bination (ooPoo).ooP.oP .'2Pgo , as in fig. 61 above, are 
often pushed sidewise into each other, as shown in fig. 91. 

In the triclinohedric system, some twin formations are ot 
great importance as a means of distinguishing the tricUno- 
hedric from the monoclinohedric species of felspar. In one 
variety the twin axis is the normal to the brachydiagonal 
chief section. But in the triclinohedric felspars this sec- 
tion is not, as it is in the monoclinohedric species, perpen- 
dicular to the basis, and consequently the two bases form 
on one side a re-entering, on the other a salient angle ; 
whereas in the monoclinohedric felspars (where the brachy- 
diagonal chief section corresponds to the clinodiagonal), no 
twin crystals can be produced in conformity to this law, and 
the two bases fall in one plane. The albite and oligoclase 
very often exhibit such twinSj as in figure 92, where the 




m 




rl\ 


^>Z^^^r^ 


fr\^ 


\ ) 


/' 


1 ^^ 


"^-•v ' 


l! 1; 






>Wl 


^ : 


Mjz 


VV 


\.t- 


' 


VjVpN 


( / 


\k' 


V 


\/ 



Fiff. 92. 



very obtuse angles formed by the faces of OP, or P and P' 
(as well as those of 'P'oo , or x and a?'), are a very charac- 
teristic appearance; marking out this mineral at once as a 
triclinohedric species. Usually the twin formation is re- 
peated, three or more crystals being combined, when those 
in the centre are reduced to mere plates. When very nu- 
merous, the surfaces P and x are covered with fine striae, 
often only perceptible with a microscope. A second law 




10 A POPULAE TREATISE ON GEMS. 

observed in triclinoliedric felspars, particularly the albite 
and labradorite, is that the twin axis corresponds with that 
normal of the -brachy diagonal which is 
situated in the plane of the base. In 
pericline, a variety of albite, these twins 
appear as in fig. 93, where the two .crys- 
tals are united by a face of the basal 
pinacoid P, while the faces of the two 
brachypinacoids (ilfand 31') form edges 
with very obtuse angles (l^S^ 22'), re- 
entering on the one side and salient on 
the other. These edges, or the line of '^' ^' 

junction between Jfand J/', are also 2^arallel to the edges 
formed by these faces and the base, or those between 3f 
and jP. In this case also the macles are occasionally sev- 
eral times repeated when the fices appear covered with fine 
striae. 

Irregular Aggregation of CrystaJs. 

Besides the regular unions now described, crystals are 
often aggregated in peculiar w\ays, to which no fixed law 
can be assigned. Thus some crystals, apparently simple, 
are composed of concentric crusts or shells, which may be 
removed one after the other, always leaving a smaller crys- 
tal like a kernel, with smooth distinct faces. Some speci- 
mens of quartz from Beeralston in Devonshire consist ap- 
parently of hollow hexagonal pyramids placed one within 
another. Other minerals, as fluor spar, apatite, heavy spar, 
and calc-spar, exhibited a similar structure by bands of dif- 
ferent colors. 

Many large crystals, again, appear like an aggregate of 
numerous small crystals, partly of the same, partly of dif- 
ferent forms. Thus some octahedrons of fluor spar from 
Schlaggenwald are made up of small dark violet-blue cubes, 



FORM OF MINERALS. Yl 

\yliose projecting angles give a driisy character to the faces 
of tlie larger form. Such poly synthetic crystals, as they 
may be called, are very common in calc-spar. 

A similar, but still more remarkable formation, is where 
two crystals of distinct species are conjoined. Such unions 
of cyanite and staurolite have been long well known, and 
the graphic-granite exhibits a similar union between large 
felspar crystals and many smaller ones of mica and quartz. 

Forms of Crystalline Aggregates. — Crystals have often 
been produced under conditions preventing the free de- 
velopment of their forms. They then compose crystalline 
aggregates, of which the following may be distinguished : — 
Granular., formed^ of grains, generally angular, but rarely 
rounded or flattened, Tjamellar ^consist of broad plates, 
which are tabular when of uniform thickness, lenticular 
when becoming thinner on the edges, loedge-sliaped when 
sharpened towards one edge, and scaly when the plates are 
very small. Colwinnar., in which the individuals are drawn 
out in one direction more than in the others ; hacillary or 
rod-like, in which the columns are of uniform thickness ; 
acicidar or needle-shaped, in which they are pomted ; and 
fibrous., in which they are very fine. In the broad-colum- 
nar the columns are, as it were, compressed, or broader in 
one direction than the other. The distinctions of large, 
"coarse, small, or fine-granular ; thick or thin scaly ; straight, 
curved, or twisted- columnar ; parallel, diverging, or con- 
fused-fibrous ; and such like, are easily understood. 

Aggregates which have been able to crystallize, at least, 
with a certain degree of freedom, have been distinguished 
by Mohs into crystal groups and druses : the former includ- 
ing all unions of several imbedded crystals ; the latter those 
of crystals that have grown together on a common support. 
^In the groups, crystals with their faces otherwise perfect 
are conjoined in various ways. Sometimes they radiate, as 



V2 A POPULAR TREATISE ON GEMS. 

it were, from a common centre, and produce spheroidal, el- 
lipsoidal, or other forms, frequent in gypsum, iron pyrites, 
and other minerals imbedded in clay. Where many such 
masses are united, they are uamed hotryoidal when like 
bunches of grapes, mammellated where the spheres are 
larger and less distinct, and reniform or kidney-shaped 
where the masses are still larger. Some groups are par- 
tially attached by a small point ; but the mass is generally 
free. 

Crystals are often grouped in rows or in one direction, 
forming, when they are very small, capillary or hair-like, 
and filiform, thread, or wire-like forms, which are common 
among native metals, as gold, silver, copper, and bismuth, 
in silver glance and a few other materials. Sometimes the 
masses are dentiform, consisting of portions resembling 
teeth ; as is very common in silver. Often these groups 
expand in several directions, and produce arborescent, 
dendritic, foliated, feathered, or other forms, very common 
in copper. In these groups, however, a certain dependence 
on the crystallographic character of the species may be 
observed. The lamellar minerals often form fan-shaped, 
wheel-like, almond-shaped, comb-like, or .other groups. 
The fibrous types, again, are disposed in parallel or diverg- 
ing bundles, or in radiating, stellar, and other masses. 
Coralloidal (like coral), fruticose (like cauliflower), and other, 
forms, have also been observed. 

In druses, many crystals rise side by side from a common 
support ; sometimes only the granular mass composed of 
their miited bases, at other times some distinct body. The 
form of a druse is determined by that of the surface on 
which it grows, and consequently is often very irregular or 
wholly accidental. Where completely inclosed they have 
been named drusy cavities, and when of a spheroidal form, 
geodes. A drusy crust, again, consists of a thin layer of 



FORM OP MINERALS. • 73 

small crystals investing the surface of a large crystal or of 
some other body. 

The minute or cryptocrystalline minerals form similar 
aggregates. In the globular or the oolitic, the minute crys- 
tals often appear to radiate from a centre, or form concen- 
tric crusts. Somewhat similar are the stalactites and sta- 
lagmites, in which the mineral, especially rock-salt, lime- 
stone, chalcedony, opal, limonite, has been deposited from 
a fluid dropping slowly from some overhanging body. In 
this case the principal axis of the figure, generally a hollow 
tube, is vertical, while the individual parts are arranged at 
right angles to this direction. In other cases the mineral 
has apparently been deposited from a fluid mass moving 
slowly in a particular direction, which may be regarded as 
the chief axis of the figure, while the axes of the indi- 
vidual crystals may assume a diflerent position. 

By far the largest masses of the mineral kingdom have, 
however, been produced under conditions in which a free 
development of their forms was excluded. This has been 
the case with the greater portion of the minerals compos- 
ing rocks or filling veins and dykes. The structure of these 
masses on the large scale belongs to geology, but some 
varieties of the texture visible even in hand specimens may 
be noticed. The individual grains or masses have seldom 
any regular form, but appear round, long, or flat, according 
to circumstances, and as each has been more or less checked 
in the process of formation. Even then, however, a cer- 
tain regularity in the position of the parts is often observ- 
able, as in granite, in which the cleavage planes, and con- 
sequently the axes of the felspar crystals, are parallel. 
Where these grains are all pretty similar in size and shape, 
the rock is named massive when they are small, or granular 
when they are larger and more distinct. Sometimes the rock 
becomes slaty, dividing into thin plates^ or concretionary, 

4 



74 A POPULAR TEEATISE ON GEMS. 

forming roundish masses ; at other times the interposition 
of sonie foreign substance (gas or vapor) has rendered -it 
porous, celhilar or vesicular, giving rise to drusy cavities. 
These cavities are often empty, but have occasionally been 
filled by other minerals, when the rock is named amygda- 
loidal, from the almond-like shape of the inclosed masses. 

Many of the above external forms appear also in the 
amorphous solid minerals, in which no trace of individual 
parts, and consequently of internal structure, is observable. 
They are not unfrequently disposed in parallel or concen- 
tric layers, of uniform or distinct colors ; and may assume 
spherical, cylindrical, stalactitic, and other apj^earances. 

Pseudomorpliisryi. — When the substance of one mineral 
assumes the external form of some other mineral, it is named 
a pseudomorph. In some named incrusting pseudomorphs 
the original crystal is covered by a rough or drusy surface 
of the second mineral, frequently not thicker than paper. 
Occasionally the first crystal has been removed, and noth- 
ing but the shell remains ; or the cavity has been filled by 
a distinct mineral species, or a crystalloid, as it may be 
named, forming an exa,ct representation of the original, but 
of a difierent substance. 

More commonly the new mineral substance has gradually 
expelled the old, and replacing it, as it were, atom by atom, 
has assumed its exact form. In other cases not the whole 
substance of the original crystal, but only one or more of 
its elements, has been changed, or the whole matter has 
remained, but in a new condition. Thus arragonite crys- 
tals have been converted into calc-spar, the chemical com- 
position of both being identical ; or gaylussite has been 
changed into calc-spar, andalusite into cyanite, by the loss 
of certain elements. On the other hand, anhydrite be- 
comes gypsum, red-copper ore malachite, by addition of 
new matter. Or the elements are partially changed, as 



I FORM OF MINERALS. 75 

felspar into kaolin, quartz or pearl spar into talc, iron pyrites 
or iron glance into brown-iron ore, azurite into iiialacliite, 
augite into green earth. The true nature of such bodies is 
shown by the internal structure, having no relation to the 
external form or apparent system of crystallization. 

The process of petrifaction of organic bodies is in reality 
a species of pseudomorphic formation, and has been pro- 
duced in all the above modes. External and internal casts 
of organic bodies are not uncommon. In other cases the 
original substance has been replaced by some mineral which 
has preserved not merely the external form, but even the 
minutest detail of internal structure ; so that the different 
kinds of wood have been distinguished in their silicified 
trunks. The most common petrifying substances are silica 

4 

and carbonate of lime. In encrynites, echinites, belemnites, 
and other fossils, the crystals of calc-spar often occur in 
very regular positions. In some varieties of petrified wood 
both the ligneous structure and the cleavage of the calc- 
spar are observable. 

Different from the above are mineralized bodies, in which 
the original structure is still retained, bitt their chemical 
nature partially changed. In these a complete series may 
be often traced, as from wood or peat, through the varie- 
ties of brown coal, common coal, anthracite, and graphite, 
perhaps even to the diamond. 



CHAPTER II. 

PHYSICAL PROPERTIES OF MINERALS. 

The physical characters of minerals comprehend, — 1st, 
Those properties derived from the nature of the substance 
itself, as coherence, mode of fracture, elasticity, and density 



76 A POPULAR TREATISE OX GEMS. • 

or specific gravity ; 2J. Those phenomena called forth in 
minerals by the influence of some external power or agent, 
as their optical, electric, or thermal relations; and, Sd. 
Other characters depending on the personal sensation of 
the observer — on his taste, smell, and touch. All these 
properties furnish useful characters in distinguishing and 
describing mineral species. 

Cleavage and Fracture. 

In many species there are certain planes at right angles' 
to which cohesion seems to be at a minimum, so that the 
mineral separates along or parallel to these planes far more 
readily than in any other direction. This property is named 
cleavage, and these planes cleavage-planes. They have a ^ 
strictly definite position, and do not show any transition or 
gradual passage into the greater coherence in other direc- 
tions. The number of these parallel cleavage-planes is alto- 
gether indefinite ; so that the only limit that can be as- 
signed to the divisibility of some minerals, as gypsum and 
mica, arises from* the coarseness of our instruments. 

These minima of coherence or cleavage-planes are always 
parallel to some fece of the crystal, and similar equal mini- 
ma occur parallel to CA^ery other face of the same form. 
Hence they are always equal in number to the faces of the 
form, and the figures produced by cleavage agree in every 
point with true crystals, except that they are artificial. 
They are thus most simply and conveniently described by 
the same terms and signs as the faces of crystals. Some 
minerals cleave in several directions parallel to the faces of 
difierent forms, but the cleavage is generally more easily 
obtained and more perfect in one direction than in the 
others. This complex cleavage is well seen in calc-spar 
and fluor spar, and very remarkably in zinc-blende, where 



I 



PHYSICAL PEOPEETIES OF MINERALS. T7 
I 

it takes place in no less than six directions. As in each of 
these the division may be indefinitely continued, it is clear 
that no lamellar structure in any proper sense can be as- 
signed to the mineral. All that can be affirmed is, that 
contio^uous atoms have less coherence in the normal of these 
planes than in other directions. When the cleavage, takes 
place in three directions, it of course produces a perfect 
crystal form, from which the system of crystallization and 
angular dimensions of the species may be discovered, and . 
is thus often of very great importance. 

The common cleavage in the different systems is as fol- 
lows, those of most frequent occurrence being 23ut in italics : 
(1.) In the tesseral, Octahedric^ O, along the faces of the 
octahedron ; Hexahedric, oo O oo , along those of the cube ; 
and Dodecahedric, goO. (2.) In the tetragonal system., 
Pyramidal, P or 2Poo ; Prismatic^ ooP or ooPoo; or J^a- 
sal^ OP. (3.) In the hexagonal system with holohedric 
forms. Pyramidal, P or P2 ; Prismatic^ coP or ooP2; or 
JBasal^ OP; with rhombohedral forms, Phorahohedric^ R; 
Prismatic, oo R ; or Pasal^ OR. (4.) In the rhombic sys- 
tem. Pyramidal, P; Prismatic^ ooP; Makro or Brachy- 
domatic. Poo or Poo; Pasal^ OP; Macrodiagonal, ooPoo; 
or PraGhydiago7ial^ qoPgo. (5.) In the monoclinohedric 
system, Hemipyramidal, Por— P; Prismatic^ ooP; Clin- 
odomatic (Poo) ; Hemidomatic, Poo or— Poo; Pasal^ OP; 
Orthodiagoncd^ ooPoo; or Clinodiagonal (coPco). (6.) 
In the triclinohedric system, Hemiprismatic, coP' oroo'P; 
Hemidomatic either along the macrodome or brachydome ; 
Pasal^ OP; Macrodiagonal, coPoo; or Pr achy diagonal^ 

00 P 00. 

In some minerals the 'cleavage is readily procured ; in 
others only with extreme difficulty. The planes produced 
also vary much in their degree of perfection, being highly 
perfect in some, as mica and gypsum ; imperfect in others, 



78 A POPULAR TEEATISE ON GEMS. 

as garnet and quartz. In a very few crystalline minerals 
cleavage-planes can hardly be said to exist. Cleavage must 
be carefully distinguished from the planes of union in twin 
crystals, and the division-planes in the laminar minerals. 

Fracture surfaces are formed when a mineral breaks in 
a direction different from the cleavage-planes. They are 
consequently most readily observed when the cleavage is 
least perfect. The form of the fracture is named conchoidal 
when composed of concave and convex surfaces like shells, 
even when nearly free from inequalities. The character of 
the surface is smooth y or splintery when covered by small 
wedge-shaped splinters adhering by the thicker end ; or* 
hackly when covered by small slightly-bent inequalities, as 
in iron and other malleable bodies ; or earthy when it shows 
only fine dust. 

HcCrdness and Tenacity. 

The hardness of minerals, or their power of resisting any 
attempt to separate their parts, is also an important charac- 
ter. As it differs considerably in the same species, accord- 
inof to the direction and the surface on wliich the trial is 
made, its accurate determination is difficult, and the utmost 
that can usually be obtained is a mere approximation found 
by comparing different minerals one with another. For 
this purpose Mohs has given the following scale : 

1. Talc^ of a white or greenish color. 

2. Rock-salt^ a pure cleavable variety, or semi-transparent uncrystallised 
gypstim, the transparent and crystallized varieties being generally too soft. 

3. Calcareous spar; a cleavable variety. 

4. Fluor spar, in whiedi the cleavage is distinct. 

5. ApatUe,lhe asparagus-stone, or phosphate of lime. 

6. Ad ularia- felspar, any cleavable variety. 

7. Roclc- crystal, a transparent variety. 

8. Prismatic topaz, any simple variety. 

9. Corundum, from Lidia, which affords smooth cleavage surfaces. 
10. The Diamond. 



PHYSICAL PEOPEETIES OF MINERALS. 79 

Two other degrees are obtained by interposing foliated 
mica between 2 and 3, and scapolite, a crystalline variety, 
between 5 and 6. The former is numbered 2*5, the lat- 
ter 5*5. 

To ascertain the hardness of a mineral, first try which of 
the members of the scale is scratched by it, and in order to 
save the specimens, begin with the highest numbers, and 
proceed downward, until reaching one which is scratched. 
Then take a fine hard file, and draw along its surface, with 
the least possible force, the specimen to be examined, and 
also that mineral in the scale whose hardness is immediately 
above the one which has been scratched. From the resist- 
ance they offer to the file, from the noise occasioned by 
their passing along it, and from the quantity of powder left 
on its surface, their relative hardness, is deduced. When, 
after repeated trials, we are satisfied to which member of 
the scale of hardness the mineral is most nearly allied, we 
say its hardness (suppose it to be felspar) is equal to 6, and 
write after it H. = 6'0. If the mineral do not exactly cor- 
respond- with any degree of the scale, but is found to be 
between two of them, it is marked by the lower with a de- 
cimal figure added. Thus, if more than 6 but less than 7, 
it is expressed H. = 6*5. In these experiments we must be 
careful to employ specimens which nearly agree in form 
and size, and also as much as possible in the shape of their 
angles. 

Where the scale of hardness is wanting, or for a first 
rough determination, the following experiments may serve : 

Every mineral that is scratched by the finger-nail has H. = 2-5 or less. 
Minerals that scratch copper have H. = 3 or m(fire. 
Polished white iron has H. = 4*5. 
Window-glass has H. = 5 to 5'5. 
Steel point or tile has II, =: 6 to 7. 

Hence every mineral that will cut or scratch with a good penknife has 
H. less than 6. 



80 A POPULAR TREATISE ON GEMS. 

Flint has H. = 7, and only a'bout a dozen minerals, including the precious 
stones or gems, are harder. 

Precious stones have latterly been divided and arranged 
according to their hardness, in the following three classes : 

1. HARD GEMS ; OR THOSE HARDER THAN QTTARTZ. 

Diamond. Topaz. 

Sapphire. Emerald. 

Ruby. Hyacinth. 

Chrysoberyl. Essonite. 

Spinelle. * Garnet. 

2. SEMI-HARD JEWELS. 

Eock Crystal. Opal. 

Amethyst. Chrysolite 

Chalcedony. Lazulite. 

Carnelian, and other Obsidian, 

similar ones. Turquoise. 

3. SOFT PRECIOUS STONES. 

Those softer than Fluor-spar ; Malachite, Amber, and Jet. 

Closely allied to hardness is the tenacity of minerals, of 
which the following varieties have been distinguished : A 
mineral is said to be brittle when, as in quartz, on attempt- 
ing to cut it with a knife, it emits a grating noise, and the 
particles fly away in the form, of dust. It is sectile or mild 
when, as in galena and some varieties of mica, on cutting, 
the particles lose their connection in a considerable degree ; 
but this takes place without noise, and they do not fly ofi*, 
but remain on the knife. And a mineral is said to be soft 
or ductile when, like native gold or lead, it can be cut into 
slices with a knife, extended under the hammer, and drawn 
into wire. From tenacity it is usual to distinguish frangi- 
hility^ or the resistance which minerals oppose when we at- 
tempt to break them into pieces oi* fiagments. This prop- 
erty must not be confounded with hardness. Quartz is 
hard, and hornblende comparatively soft ; yet the latter is 



PHYSICAL PROPEETIES OF MINEEALS. 



81 



more difficultly frangible than the former. Flexibility 
again expresses the property possessed by some minerals 
of bending without breaking. They are elastic^ like mica, 
if^ when bent, they spring back again into their former di- 
rection ; or merely flexible, when they can be bent in dif- 
ferent directions without breaking, but remain in their new 
position, as gypsum, talc, asbestus, and all malleable min- 
erals. 



Bpecijic Gravity. 

The density or the relative weight of a mineral, com- 
pared with an equal volume of pure distilled water, is named 
its specific gravity. This is a 
most important character for dis- 
tinguishing minerals, as it varies 
considerably in different species, 
and can be readily ascertained 
with much accuracy, and in many 
cases without at all injuring the 
specimen. The whole process con- 
sists in weighing the body, first in 
air, and then immersed in water, 
the difference in the weight being 
that of an equal bulk of the latter 
fluid. Hence, assuming, as is com- 
monly done, the specific gravity 
of pure distilled water to be equal 
to 1 or unity, the specific gravity 
(G) of the other body is equal to its weight in air (io), di- 
vided by the loss or difference (G) of weight in water (or 

G=-). A simple and portable instrument for finding the 

specific gravity is'* a hydrometer of Nicholson, fig. 94. A 

delicate hydrostatic balance gives the gravity with far more 

4<s " ^ 




Fig. 94. 



82 A POPULAR TREATISE ON GEMS. 

accuracy ; and even a good common balance is often pref- 
erable. The mineral may be suspended from one arm or 
scale by a fine silk thread or hair, and its weight ascer- 
tained, first in the air, and then in water. 

There are a few precautions necessary to insure accuracy. 
Thus, a pure specimen must be selected which is not inter- 
mixed with other substances, and when weighed in air it 
should be quite dry. It must also be free from cavities, 
and care must be taken that when weighed in water no 
globules of air adhere to its surface, which render it lighter. 
If the body imbibes moisture, it should be allowed to re- 
main till fully saturated before determining its weight when 
immersed, and it is sometimes even necessary to boil the 
specimen in order to e>:pel the air from its pores. Small 
crystals or fragments, whose freedom from mixture can be 
seen, are best adapted for this purpose. The specimen 
experimented on should not be too heavy ; thirty grains 
being enough where the gravity is low, and even less where 
it is high. It is also of importance to repeat the trial, if 
possible with different specimens, which will show whether 
any cause of error exists, and to take the mean of the 
whole. A correction should be made for the variation of 
the temperature of the water from 60° Fahr., which is that 
usually chosen as the standard in mineralogical works. 
Where the difference, however, does not exceed ten or fif- 
teen degrees, this correction may be neglected, as it only 
affects the third or second decimal figure of the result. 

By determining the specific gravity of minerals with the 
hydrostatic balance, we proceed, for instance : an unknown 
mineral having been weighed first in the air, and then fast- 
ened by means of a hair and weighed in water. Such as 
in the air 17 '65; in water 12'35. The loss in water is, 
therefore, 5*30; and this number indicates the loss of so 
much bulk of water displaced by the mineral putting the 



PHYSICAL PROPERTIES OF MINERALS. 83 

specific gravity of water 1*00: x dividing 5 into 17"65, 
make it equal to 3 5 3, which is the exact specific gravity 
of the mineral, and which is that of essonite. Instead of a 
hydrostatic balance, we may as well use I^^icholson's hy- 
drometer, a simple and very convenient instrument, con- 
sisting of a hollow glass cylinder (A), and two dishes (B 
and C) filled with lead, in order to keep the instrument 
upright. The hydrometer is put in a glass vessel (E), filled 
with water, and used as follows : 

1st. The weight is determined which is required to sink 
the instrument to the mark D in water. 

2d. The mineral is put in the dish A over the weight 
noted, that is required, in addition to the mineral, to sink 
the hydrometer to D. 

3d. The same experiment is repeated by putting the 
mineral, after being moistened and washed with water, in 
the dish C ; and now is A— B the weight of the mineral in 
the air, and B— b the weight of a quantity of water equal 
in volume to that of the mineral. 

For instance, let A = 32'8 

B = 7*3 
C = 15-8 
there is (A— b) 32-8 — 7-3 = 25*5 the weight of the mineral 
in the air. 

(C— b) 15-8 — 7*3 = 8*5 the weight of an equal quantity 
of water, and proceed 8'5 : 25*5 = 1 : x 

x = 25'5 



8-5 



= 3*00, which is the pro]3er specific 
gravity. For determining the specific gravity of substances 
or minerals lighter than water, or which float in water, it 
is necessary to adhere to the same method by the hydrome- 
ter. A heavier body, such as lead, after determining the 



84 A POPULAR TREATISE ON GEMS. 

difference of weight, within or without the water, of both 
together, and then of the heavier body alone, the specific 
gravity of the lighter substance is the result. And for de- 
termining the specific gravity of liquids, by means of the 
hydrostatic balance, a glass ball is applied to one of the 
arms (its loss of weight in pure water being known), and, 
dipping the same in the liquid to be examined, any addition 
and abstraction will result in the specific gravity of the 
liquid. The hydrometers of Beaume for the different 
liquids to be examined, are employed with satisfactory 
results. 

That the specific gravity has been known as far back as 
the thirteenth century, and applied by the Oriental nations 
for determining the character of precious stones, is suffi- 
ciently proved by a work written in that century by Mo- 
hammed Ben Manner. In fact, the specific gravity is often, 
in connection with the color, quite essential in determining 
a gem. 

Optical Properties of 3Iinerals. 

There are few more interesting departments of science 
than the relations of mineral bodies to light, and the modi- 
fications which it undergoes either when passing through 
them or when reflected from their surface. In this j^lace, 
however, we can only notice these phenomena so far as 
they point out distinctions in the internal constitution of 
minerals, or furnish characters for distinguishing one species 
from another. 

Minerals, and even different specimens of the same spe- 
cies, vary much in pellucidity or in the quantity of light 
which can pass through them. Some transmit so much 
light, that small objects can be clearly seen, or letters read 
when placed behind them, and are named transparent. 
They are semi-transparent Avhen the object is only seen 



PHYSICAL PEOPEETIES OF MINERALS. 85 

dimly, as through a cloud ; and translucent when the light 
that passes through it is so obscured that the objects can 
be no longer discerned. Some minerals are only thus trans- 
lucent on the thinnest edges^ and in others even these trans- 
mit no light, and the body is named opaque or untranspa- 
rent. These degrees pass gradually into each other, and 
cannot be separated by any precise line ; and this is also 
the case in nature, where some minerals pass through the 
whole scale, as quartz, from the fine transparent rock-crys- 
tal .to opaque dark-black varieties. Such minerals may be 
described generally as pellucid. This'change often arises 
from some mixture in their composition, especially of me- 
tallic substances. Perfect opacity is chiefly found in the 
metals or their compounds with sulphur, though even these 
seem to transmit light when reduced to laminae of suflicient 

thinness. 

« 

Double Mefraction. — When a ray of light j)asses ob- 
liquely from one medium into another of difierent density, 
it is bent or refracted from its former course. The line 
which it then^ follows forms an angle with the perpendicu- 
lar, which in each body bears a certain proportion to 
that at which the ray fell upon it ; or, as definitely stated, 
the sine of the angle of refraction has a fixed ratio to the 
sine of the angle of incidence, this ratio being named the 
index of refraction. This simple refraction is common to all 
transparent bodies, whether crystalline, amorphous, or fluid ; 
but some crystals produce a still more remarkable result. 
The ray of light which entered them as one is divided into 
two rays, each following different angles, or is doubly re- 
fracted. In minerals of the tesseral system this property 
does not exist, but it has been always observed in minerals 
belonging to the other systems, though in many only after 
they have been cut in a particular manner, or have been 
otherwise properly prepared. It is most distinctly seen in 



A POPULAR TREATISE ON GEMS. 




Fig. 95. 



crystals of calc-spar, especially in the beautiful transparent 
variety from Iceland, in which it was first observed and 
described by Erasmus Bartholin in a work published at 
Copenhagen in 1669. 

The subjoined figure will illustrate this singular proper- 
ty. It represents a 
rhomb of Iceland 
sjjar, on the surface 
of which a ray of 
light J? r falls. As 
seen in the figure,' 
this ray divides into 
two, one of which 
roo follows the ordi- 
nary law of refrac- 
tion, or the sines of 
the angles of incidence and refraction maintain a constant 
ratio. This is named the ordinary ray O. The other, 
hence named the extraordinary ray E, does not obey the 
usual law of the sines, and has no general index of refrac- 
tion. In the plane perpendicular to the axis it is most 
widely separated from the ordinary ray, but in others ob- 
lique to it approaches nearer to O, and in one at right 
angles coincides, or there is no double refraction. This 
plane, or rather direction, in which there is no double re- 
fraction, is named the optical axis of the crystal, or the 
axis of double refraction. Now, in certain minerals, it is 
found that there is only one plane with this property, where- 
as in others there are two such planes, and they have in 
consequence been divided into monoaxial and binaxial. To 
the former (monoaxial) belong all crystals of the tetrago- 
nal and hexagonal systems ; to the latter (binaxial) all 
those of the three other systems. In the former the optic 
axis coincides with, or is parallel to, the crystallographic 



PHYSICAL PROPERTIES OF MINERALS. 87 

chief axis. In some crystals the index of refraction for the 
extraordinary ray E is greater than for the ordinary ray O ; 
aiid in others it is smaller. The former are said to have 
positive (or attractive), the latter negative (or repulsive), 
double refraction. Quartz is an example of the formei*, 
the index of refraction, according to Malus, being for = 
1'5484, for E=1'5582; and calc-spar of the latter, the 
index of O beings 1-6543, of £=1-4833. The index of 
E is in both cases taken at its maximum. 

According to Dufrenoy, the following table shows the 
index of refraction of a great number of minerals : 

Chromate of lead .2-500 to 2-974 

Diamond 2-439 to 2-755 

Native sulphur 2-115 

Carbonate of lead .' 2-084 

Zircon 1 -950 

Garnet 1-815 

Spinelle 1 -812 

• Blue corundum (sapphire) 1-794 

Eed " (ruby) 1-779 

White " (sapphire) 1-768 

Adularia 1-764 

Cymophane (oriental chrysolite) 1-760 

Boracite 1-701 

Carbonate strontia 1-700 

„ , ,. 1 ordinary ray 1-654 

Carbonate lune •{ 

( extraordmary ray 1-483 

. . (ordinary ray 1-693 

Arragonite < ,. 

I extraordinary ray 1 "535 

„ , , , , ( one of the rays 1-635 

Sulphate baryta | ^^^ ^^^^^^ ^^^, ^.^^^ 

„ ,, ^ ( one of the rays .1-640 

Yellow topaz-} , , • - „„„ 

^ { the other ray 1-632 

White topaz 1*610 

. , , . ( one of the rays. . . ; 1-624 

^^^y^^^^H the other ray 1-577 

Euclasej^^'^^^^'^y'"'^' '*'^' 



Quartz -j 



extraordinary ray 1-663 

ordinary ray 1-548 

extraordinary ray 1*558 



88 A POPULAR TREATISE OX GEMS. 

Eock salt 1-557 

Chalcedony 1*553 

Gypsum 1 '525 

Opal 1-479 -• 

Eorax •. 1 "475 

Alum 1-457 

Fluor spar 1-436 

The higher the index of refraction, the more valuable 
appear to be the individual minerals, as may be seen by 
the corundum and topaz. 

Double refraction, whether positive or negative, being 
inherent in the respective mineral substances, forms a very 
important distinctive character, and the following minerals 
are arranged according to this property : 

■ CRYSTALS "WITH ONE AXIS AND NEGATIVE DOUBLE REFRACTION. 

Iceland spar. Anatase. 

Dolomite. Tourmaline. 

Carbonate iron. Eubellite. 

Carbonate zinc. Corundum. 

Meionite. Emerald. 

Somervillite. Phosphate lime. 

Edingtonate. Idocrase. 

Wernerite. Mellite. 

Mica. Arseniate copper. 

Phosphate lead. Nepheline. 

Arseniate " Ked silver. 

Molybdate " Dioptase. 

Cinnabar. Alum. 

CRYSTALS WITH ONE AXIS AND POSITIVE DOUBLE REFRACTION. 

Zircon. Hydrate magnesia. 

Quartz. Eutil. 

Hydroxide iron. Oxahverite. 

Oxide tin. Calcareous Scheelite. 

Apophyllite. Iron. 

It should be observed that the optic axes are not single 
lines, but directions parallel to a line, or innumerable par- 



I 



PHYSICAL PEOPEKTIES OF MINEEALS. 89 

allel lines, passing through every atom of the crystal. It 
is also important to remark that this property divides the 
systems of crystallization into three precise groups, — the 
tesseral, with single refraction ; the tetragonal and hexago- 
nal, with double refraction, and monoaxial ; the other three 
systems also double, but binaxial. It is therefore of use to 
determine the system to which a mineral belongs, but is 
not of great value as a character for distinguishing species. 
Polarization of Light. — Intimately connected with this 
property is that of the polarization of hght, which being 
more easily and precisely observable than double refraction, 
is in many cases of higher value as a mineralogical character. 
By this term is meant a peculiar modification which a ray 
of light undergoes, in consequence of which its capability 
of being transmitted or reflected towards particular sides 
is either wholly or partially destroyed. Thus, if fi-om a 
transparent prism of tourmaline two thin plates are cut 
parallel to its axis, they will transmit light, as well as the 
prism itself, when they are placed above each other with 
the chief axis of both in the same direction. But when 
the one slip of tourmaline is turned at right angles to the 
other, either no light at all or very little is transmitted, and 
the plates consequently appear black. Hence, in passing 
through the first slip the rays of hght have acquired a pe- 
culiar property, which renders them incapable of being 
transmitted through the second, except in a parallel posi- 
tion, and they are then said to be polarized. -The same 
property is acquired by a ray of light when reflected, at 
an angle of 35 J° (or angle of incidence 54^°), from a plate 
of glass, one side of which is blackened, or from some 
other non-metallic body. When such a ray falls on a 
second similar mirror at an equal angle, but so that the 
plane of reflection in the second is at right angles to that 
in the first, it is no longer reflected, but wholly absorbed. 



90 



A POPULAR TREATISE ON GEMS. 



When, on the other hand, the planes of reflection are 
parallel, the ray is wholly and at any intermediate angle 
partially reflected. A ray of light polarized by reflection 
is also incapable of transmission through a tourmaline slip 
in one position, which, however, is at right angles to that 
in which a ray j^olarized by passing through another slip 
is not transmitted. 

In order to observe the polarization of light, a very sim- 
ple instrument will 
be found useful (fig. 
96). At one end of 
a horizontal board 
B a black mirror a 
is fixed. In the 
middle is a pillar 
to which a tube c d 
is fastened, with its 
axis directed to the 
mirror at an angle 
of 35^. On the 
lower end is a cover c, with a small hole in the centre, and 
at the upper end another cover with a small black mirror 
m attached to it by two arms, as in the figure, and also at 
an angle of 35 1°. With this instrument the mirror m can 
be so placed in relation to a that the planes of reflection 
shall have any desirable inclination to exhibit the simple 
polarization of light. 

This instrument furnishes a simple test whether minerals 
that, cleave readily into thin lamellae are optically mono- 
axial or binaxial. Place the two mirrors with their polari- 
zation-planes at right angles, and fix a plate of the mineral 
with a little wax over the hole c, and then observe what 
takes place in the second mirror during the time that the 
cover c is turned round. If the mineral belongs to the bi- 




i 



PHYSICAL PROPERTIES OF MINERALS. 91 

naxial system, the light from the first mirror a, in passing 
through it, is doubly refracted and has its polarization 
changed, and consequently can be again reflected from the 
second mirror ?n, and in each revolution of c will show four 
maxima and four minima of 
intensity. If, on the contrary, 
the mineral is monoaxial, the 
ray will pass through the lami- 
na unaltered, and will not be 
reflected from the second mir- 
ror in any posftion of c. 

Another beautiful phenom- 
enon of polarized light, in like 
manner connected with the 
crystalline structure of miner- 
als, is the colored rings which 




iinH 

iliSiili 

Fig. 97. 











Fig. 93. Fig. 99. 

laminae of the doubly-refracting species, when of a proper 
thickness, exhibit in certain positions. These rings are 



92 A POPULAR TREATISE ON GEMS. 

easily seen in the above apparatus by interposing a thin 
plate of gypsum or mica between the two mirrors. When 
tKe interposed plate belongs to a monoaxial mineral, there 
is seen in the second mirror a system of circular concentric 
colored rings intersected by a black cross (fig. 97). If the 
mineral is binaxial, one or two systems of elliptical colored 
rings appeiir, each intersected by a black stripe (fig. 98). 
In certain cases this stripe is curved, or the two systems of 
rings unite in a lemniscoidal form (fig. 99). When the 
planes of polarization are parallel, the 
black cross and stripe appear white ^^^^ ^^^. 
(fig. 100), showing that in this direc- ^^^^^ ^^^^^k 
tion the crystals act Uke singly-refract- fffj^^^ ^^^^\i 
ing minerals. Quartz, again, in close = - - = ^ ^^"^ ^ ! ^ I ". ! 
relation to its system of crystalliza- 1%^^^^ ^^£iiM 
tion, exhibits a circular polarization ^^^^^ ^^^^^ 
of splendid prismatic colors, which, ^^^p ^^y^ 
on turning the plate, change in each ^ig. loo. 

point in the order of the spectrum, 

from red to yellow, green, and blue. In order to produce 
these changes, however, in some specimens the plate must 
be turned to the right, in others to the left, showing a dif- 
ference in the crystalline structure. 

Pleochroism. — Closely connected with double refraction 
is that property of transparent minerals named pleochroism 
(many-colored), in consequence of which they exhibit dis- 
tinct colors when viewed by transmitted light in diflferent 
directions. Crystals of the tesseral system do not show 
this property ; while in those of the other systems it ap- 
pears in more or less perfection ; and in the tetragonal and 
hexagonal minerals as dichroism (two colors), in the rhom- 
bic and clinohedric systems as trichroism (three colors). 
In most cases these changes of color are not very decided, 
and appear rather as different tints or shades than as dis- 



PHYSICAL PROPERTIES OF MINERALS. 93 

tinct colors. The most remarkable of dichromatic minerals 
are the magnesian mica from Vesuvius, the tourmaline and 
ripidolite ; of trichromatic, the iolite, the andalusite from 
Brazil, the diaspore from Schemnitz, and the axinite. 

Change of Colors — Changing Colors — Iridescence. 

Some crystalline minerals exhibit a very lively play or 
change of colors from reflected light in certain directions. 
It is well seen in many various hues on the cleavage-planes 
of Labrador felspar, and seems produced by a multitude of 
very thin quadrangular pores, interposed in the mineral 
like minute parallel laminge. On the cleavage-planes of the 
hypersthene it appears copper-red, and is occasioned by 
numerous small brown or black laminae of some foreign 
substance interposed in a parallel position between the 
planes of the hypersthene. The chatoyant, or changing 
colors of the sun-stone, arise from scales of iron-glance simi- 
larly interposed. The play of color in the noble opal seems 
to be produced very nearly in the same manner with that 
in the labradorite. A similar opalescence is seen in certain 
minerals when cut in particular forms. In the sapphire, 
cut hemispherically over the chief axis, it appears like a 
star with six rays ; in certain varieties of chrysoberyl and 
adularia it has a bluish tint ; and is also very remarkable in 
the cat's-eye variety of quartz. Iridescence often arises 
from very fine fissures, producing semicircular arches of 
prismatic tints, which, like the colors of thin plates in gen- 
eral, are referred to the interference of light. 

Lustre and Color. 

Though these properties admit of no precise or mathe- 
matical determination, they are of considerable value in 



94 A POPULAR TREATISE OX GEMS. 

mineralogy. One highly important distinction founded on 
them is that of minerals of metallic and non-metallic aspect 
or character. This distinction can hardly be described in 
words, and the student will best learn to distinguish metal- 
lic colors and lustre from non-metallic by observing them 
in nature. Transparency and opacity nearly coincide with 
this division, the metallic minerals being almost constantly 
opaque ; the non-metallic more or less transparent. Min- 
erals which are perfectly opaque, and show metallic color 
and lustre, are named metallic ; those with only two of 
these three properties, semi-metallic or metalloid ; and those 
with the opposite properties non-metallic. 

Liistre has reference to the intensity and quality of the 
reflected light, considered as distinct from color. Several 
degrees in intensity have been named, (l.) Splendent^ 
when a mineial reflects light so perfectly as to be visible at 
a great distance, -and lively, well-defined images are formed 
in its faces, as galena, rock-crystal, or calc-spar. (2.) 
Shining^ when the reflected Ught is weak, and only forms 
indistinct and cloudy images, as heavy spar. (3.) Glisten- 
i7ig^ when the reflected light is so feeble as not to be ob- 
servable at a greater distance than arm's length, and the 
surface can no longer form an image. (4.) Glimmering^ 
when the mineral held near the eye in full clear daylight 
presents only a number of small shining points, as red 
hasmatite and granular limestone. When, as in chalk, the 
lustre is so feeble as to be indiscernible, it is said to be dull. 

In regard to the kind or quality of the lustre, the follow- 
ing varieties are distinguished: — (1.) The m^etallic, seen in 
much perfection in native metals and their compounds with 
sulphur, and imperfectly in glance coal. (2.) Adamantine^ 
found in beautiful perfection in the diamond, and in some 
varieties of blende and carbonate of lead. (3.) Vitreous ov 
glassy, seen in rock-crystal or common glass, or inclining 



PHYSICAL PEOPERTIES OF MINERALS. 95 

to adamantine in flint-glass. (4.) Hesinous, when the body 
appears as if smeared with oil, as in pitch-stone and garnet. 
(5.) Pearly^ like mother-of-pearl, seen in stilbite, gypsum, 
mica. (6.) Silky ^ the glimmering lustre seen on fine fibrous 
ao-o-reo-ates like amianthus. 

Color. — This property is not in all cases of equal value 
as a character. Thus some minerals are naturally colored, 
showing in all modes of their occurrence one determinate 
color, which is therefore essential, and forms a characteristic 
of the species. This class includes the metals, pyrites, 
blendes, with many metallic oxides and salts. A second 
class of minerals are colorless, their purest forms being 
white, or clear like water, as ice, calc-spar, quartz, adularia, 
and many silicates. But these minerals are occasionally 
colored — that is, accidentally tinged, sometimes from the 
chemical or mechanical admixture of some coloring sub- 
stance, as a metallic oxide, carbon, or particles of colored 
minerals ; at other times from the substitution of a colored 
for an uncolored isomorphous element. The colors of these 
minerals therefore vary indefinitely, and can never charac- 
terize the species, but only its varieties. Thus, quartz, 
calc-spar, fluor spar, gypsum, and felspar are often colored 
accidentally by pigments mechanically mixed ; and horn- 
blende, augite, garnet, and other colorless silicates,, acquire 
green, brown, red, or black tints from the introduction of 
the isomorphic coloring elements. 

Werner, who bestowed much attention on this portion 
of mineralogy, distinguished eight principal colors, — white, 
gray, black, blue, green, yellow, red, and brown, — each 
with several varieties or shades arisino; from intermixture 
with the other colors. He also divided them into metallic 
and non-metallic as follows : 



96 A POPULAR TREATISE ON GEMS. 



METALLIC COLORS. 

1. White. — (1.) Silver- white, as ia leucopyrite and native silver. (2.) 
Tin-white ; native antimony. 

2. GruT/. — (1.) Lead-gray; galena or lead glance. (2.) Steel-gray; na- 
tive platina. 

3. Black. — (1.) Iron-black; magnetite. 

4. Yellow. — (1.) Brass-yellow; chalcopyrite. (2.) Bronze-yellow; iron 
pyrites. (3.) Gold-yellow; native gold. 

6. Red. — (1.) Copper-red ; native copper and nickeline. 

NON-METALLIC COLORS. 

1. White. — (1.) Snow-white ; new-fallen snow, Carrara marble, and 
common quartz. (2.) Reddish-white; heavy spar. (3.) Yellowish- white; 
chalk. (4.) Grayish-white ; quartz. (5.) Greenish-white ; amianthus. 
(6.) Milk-white ; skimmed milk, chalcedony. 

2. Gray. — (1.) Bluish-gray; limestone. (2.) Pearl-gray; porcelain jas- 
per, and rarely quartz. (3.) Smoke-gray or brownish-gray ; dense smoke, 
dark varieties of flint. (4.) Greenish-gray; clay-slate and whet-slate. (5.) 
Yellowish-gray; chalcedony. (6.) Ash-gray; wood-ashes, zoisite, zircon, 
and slate-clay. 

3. Black. — (1.) Grayish-black; basalt, Lydian stone, and lucullite. (2.) 
Velvet-black; obsidian and schorl. (3.) Pitch-black or brownish-black; 
cobalt ochre, bituminous coal, and some varieties of mica. (4.) Greenish- 
black or raven-black ; hornblende. (5.) Bluish-black; fluorspar. 

4. Blue. — (1.) Blackish-blue; dark varieties of azurite. (2.) Azure-blue; 
bright varieties of azurite and lapis lazuli. (3.) Violet- blue; amethyst' 
and fluor spar. (4.) Lavender-blue ; lithomarge and porcelain jasper. 
(5.) Plum-blue; spinel and fluor spar. (6.) Berlin-blue; sapphire, rock- 
salt, cyan^te, (7.) Smalt-blue; pale-colored smalt, gypsum. (8.) Duck- 
blue ; talc and corundum. (9.) Indigo-blue; earthy-blue iron orvivianite. 
(10.) Sky-blue; liroconite, some varieties of fluor spar and of blue spar. 

5. Green. — (1.) Verdigris-green; amazon stone and liroconite. (2.) Cel- 
andine-green; green earth, Siberian and Brazilian beryl. (3.) Mountain- 
green; beryl, aqua-marine topaz. (4.) Leek-green; common actynolite 
and prase. (5.) Emerald-green; emerald, and some varieties of green 
malachite. (6.) Apple-green; chrysoprase. (7.) Grass-green; uranite, 
smaragdite, (8.) Blackish-green; augite and precious serpentine. (9.) 
Pistachio-green; chrysolite and epidote. (10.) Asparagus-green; the 
apatite or asparagus- stone from Spain and Salzburg. (11.) Olive-green ; 
garnet, pitch-stone, and olivine. (12.) Oil-green; olive-oil, blende, beryl. 
(13.) Siskin-green; uranite, and some varieties of pyromorphite. 

6. Yellow. — (1.) Sulphur-yellow; native sulphur. (2.) Straw-yellow; 



; 



PHYSICAIi PEOPEETIES OF MINERALS. 97 

pycnite and karpholite. (3.) "Wax-yellow; opal and wiilfenite. (4.) Hon- 
ey-yellow; dark honey, fluor spar, and beryl. (5.) Lemon-yellow; riud 
of ripe lemons, orpiment. (6.) Ochre-yellow; yellow-earth and jasper. 
(7.) Wine-yellow; Saxon and Brazilian topaz and fluor spar. (8.) Cream- 
yellow or Isabella-yellow ; bole from Strigau, and compact limestone. (9.) 
Orange-yellow, rind of the ripe orange, uran-ochre, and some varieties of 
wulfenite. 

1. Red. — (1.) Aurora, or morning-red; realgar. (2.) Hyacinth-red ; hya- 
cinth or zircon, and garnet. (3.) Tile-red; fresh-burned bricks, porcelain- 
jasper, and heulandite. (4.) Scarlet-red; light-red cinnabar. (5.) Blood- 
red ; blood, pyropc. (6.) Flesh-red ; felspar and barytes. (7.) Carmine- 
red ; carmine, spinel, particularly in thin splinters. (8.) Cochineal-red; 
cinnabar and certain garnets. (9.) Crimson-red ; oriental ruby and eryth- 
rine. (10.) Columbine-red; precious garnet. (11.) Eose-red; diallogite 
and rose-quartz. (12.) Peach-blossom red ; blossoms of the peach, red 
cobalt-ochre. (13.) Cherry-red; spinel, kermes, and precious garnet, 
(14.) Brownish-red; reddle and columnar-clay ironstone. 

8. Bro^on. — (1.) Eeddish-brown ; brown blende from the Hartz, and 
zircon. (2.) Clove brown ; the clove, rock-crystal, and axinite. (3.) Hair- 
brown ; wood-opal and limonite. (4.) Broccoli-brown ; zircon. (5.) 
Chestnut-brown; Egyptian jasper. (6.) Yellowish-brown; iron flint and 
jasper. (7.) Pinchbeck-brown; tarnished pinchbeck, mica. (8.) Wood- 
brown ; mountain wood and old rotten wood. (9.) Liver-brown ; boiled 
liver, common jasper. (10.) Blackish-brown ; mineral pitch and brown 
coal. 

The accidentally-colored minerals sometimes present two 
or more colors or tints, even on a single crystal ; very re- 
markable examples occurring in fluor spar, apatite, sapphire, 
amethyst, tourmaline, and cyanite. This is still more com- 
mon in compound minerals, on which the colors are va- 
riously arranged in points, streaks, clouds, veins, stripes, 
bands, or in brecciated and ruin-like forms. Some miner- 
als again change their color from exposure to the light, 
the air, or damp. Sometimes merely the surface is aiFected 
or tarnished^ and then appears covered as with a thin film, 
producing in some minerals, as silver, arsenic, bismuth, only 
one color ; in others, as copper pyrites, hsematitcj stibine, 
and common coal, various or iridescent hues. Occasionally 
the change pervades the whole mineral, the color some- 

5 



98 A POPULAR TREATISE ON GEMS. 

times becoming paler, or disappearing, as in clirysoprase 
and rose-quartz ; at other times darkei", as in brown spar, 
siderite, and rhodonite. In a few minerals a complete 
change of color takes place, as in the chlorophaeite of the 
Western Isles, which, on exposm-e for a few hours, passes 
from a transparent yellow-green to black. These mutations 
seem generally connected with some chemical change. The 
tarnished colors sometimes only appear on certain faces of 
a crystal belonging to a peculiar form. Thus a crystal of 
copper pyrites (like fig. 35) has one face P' free from tar- 
nish ; the faces h and c, close to P', are dark blue ; the re- 
mainder of c, first violet, and then, close to P, gold-yellow. 
The color of the powder formed when a mineral is scratched 
by a hard body is often different from that of the solid 
mass. This is named the streaky and is very characteristic 
of many minerals. It also often shov/s a peculiar lustre 
where the mineral is soft, as in talc and steatite. 

Phosphorescence^ Electricity^ Magnetism. 

Phosphorescence is the property possessed by particular 
minerals of producing light in certain circumstances with- 
out combustion or ignition. Thus some minerals appear 
luminous when taken into the dark after being for a time 
exposed to the sun's rays, or even to the ordinary daylight. 
Many diamonds and calcined barytes exhibit this property 
in a remarkable degree ; less so, arragonite, calc-spar, and 
chalk ; and in a still inferior degree, rock-salt, fibrous gyp- 
sum, and fluor spar. Many minerals, including the greater 
part of. those thus rendered phosphorescent by the influ- 
ence of the sun, also become so through heat. Thus some 
topazes, diamonds, and varieties of fluor spar, become lumi- 
nous by the heat of the hand ; other varieties of fluor spar 
9,nd the phosphorite require a temperature near that of boil- 



PHYSICAL PEOPEKTIES- OF MliN^EEALS, 99 

ing water; while calc-spar and many silicates are only 
phosphorescent at from 400° to 700° Fahr. Electricity 
produces it in some minerals, as in green fluor spar and 

■ calcined barytes. In others it is excited when they are 
struck, rubbed, split, or broken ; as many varieties of zinc- 
blende and dolomite when scratched with a quill, pieces of 
quartz when rubbed on each other, and plates of mica when 
suddenly separated. 

» Friction, pressure, and heat also excite electricity m 
minerals. To observe this property, delicate electroscopes 
are required, formed of a light needle, terminating at both 
ends in small balls, and suspended horizontally on a steel 
pivot by an agate cup. Such an instrument can be nega- 
tively electrified by touching it. with a stick of sealing-wax, 
excited by rubbing, or positively when the wax is only 
broufyht so near as to attract the needle. When the in- 
strument is in this state the mineral, if also rendered elec- 
tric by heat or friction, will attract or repel the needle ac- 
cording as it has acquired electricity of an opposite or 
similar kind ; but if the mineral is not electric, it will at- 
tract the needle in both conditions alike. Most precious 
stones become electrical from friction, and are either posi- 
tive or negative according as their surface is smooth or 
rough. Pressure even between the fingers will excite dis- 
tinct positive electricity in pieces of transparent double- 
refi-acting calc-spar. Topaz, arragonite, fluor spar, car- 
bonate of lead, quartz, and other minerals show this 
property. 

Heat or change of temperature excites electricity in many 
crystals, as in tourmaline, calamine, topaz, calc-spar, beryl, 
barytes, fluor spar, diamond, garnet, and others, which are 
hence said to be thermo or pyroelectric. Some acquire 
polar pyro-electricity, or the two electricities appear in op- 
posite parts of the crystal, which are named its electric 



100 A POPULAR TREATISE ON GEMS. 

poles. Each pole is alternately positive and negative, — the 
one when the mineral is heating, the other when it is cool- 
ing. The poles that become positive during an increase of 
temperature are named analogue ; those that become nega- 
tive in the same condition, antilogue poles, as showm in this 
table : 



Temperature. 


Produces 


Electricity. 


-\- or rising ) 


in analogue 


-\- or vitreous. 


— or falling j 


poles 


— or resinous. 


~\- or rising 


in antilogue 


j — or resinous. 


- or falling 


poles 


I -|- <jr vitreous. 



As already noticed, many polar electric minerals are also 
remarkable for their hemimorphic crystal forms. The num- 
ber and distribution of the poles likewise vary. In many 
monoaxial minerals, as tourmaline and calamine, there are 
only two poles, one at each end of the chief axis ; whereas 
boracite has eight poles corresponding to the angles of the 
cube. In prehnite and topaz, again, two antilogue poles 
occur on the obtuse lateral edges of the prism ooP, and 
one analogue pole corresponding to the macrodiagonal 
chief section, or in the middle of the diagonal joining the 
obtuse edges. The power of retaining the electricity ac- 
quired by rubbing, for a longer time, varies in different 
minerals and gems ; and as the latter are all electric, this 
property may sometimes be used as a distinguishing char- 
acter as to the length of retaining the electricity. Abbe 
Hatiy found, in his experiments, that many jDrecious stones 
lose their electric power after a few moments, whereas some 
will retain the same for twenty-four hours longer. The 
Brazilian topaz affected the needle, even after thirty-two 
hours. 

Magnetism^ or the power to act on the magnetic needle, 
is very characteristic of the few minerals in which it occurs, 
chiefly ores of iron or nickel. It is either simple, attracting 



/ 



PHYSICAL PKOPERTIES OF MINERALS. 101 

both poles of the needle ; or polar, when one part attracts, 
and another repels the same pole. Some magnetic iron 
ores, or natural magnets, possess polar magnetism ; while 
the common varieties, meteoric iron, magnetic pyrites, 
precious garnet, and other minerals, are simply magnetic. 
Most minerals are only attracted by the magnet, but do 
not themselves attract iron. 

Smelly taste^ and touch furnish a few characters of min- 
erals. Most have no smell, but some .give out a peculiar 
odor when rubbed : as quartz, an empyreumatic odor, or 
smell of burning ; iluor spar, of chlorine ; clay, of. clay ; 
some limestones and marls, of bitumen, or a fetid odor. 
Aluminous minerals acquire a smell when breathed on. 
Other odors caused by heat, and often highly character- 
istic, are noticed under tests by the blowpipe. 

Taste is produced by all the salts soluble in water. 
Some are saline, like common salt; sweetish astringent, 
like alum ; astringent like blue vitriol ; bitter, like epsom 
salts ; cooling,' like saltpetre ; pungent, like sal-ammoniac ; 
alkaline, like soda ; acid or sour, like sassoline, &c 

Touch. — Some minerals are distinguished by a greasy 
feeling, like talc ; others feel meagre, like clay ; others cold. 
The last character readily distinguishes true gems from 
their imitations in glass. 



102 A POPULAR TREATISE ON GEMS. 



CHAPTER III. 

CHEMICAL PROPERTIES OF MINERALS. 

The consideration of the chemical nature of minerals, — 
that is, of the elements that enter into their composition, — 
of the manner in Avhich these elements combine, and the 
variations in proportion which they may undergo without 
destroying the identity of the species, forms an impoi-tant 
branch of mineralogical science. The methods of detect- 
ing the different elements, and the characters which are 
thus furnished for the discrimination of minerals, are also 
of much value. This is especially true of the metallic ores 
and other substances, sought not as objects of curiosity, 
but for their economic qualities. 

Composition of Minerals. 

At present about sixty elements, or substances Avliich 
have not been decomposed, are known. These are divided 
into metallic and non-metallic, a distinction of importance 
in mineralogy, though not always to be carried out with 
precision. The non-metallic elements are rarely of semi- 
metallic aspect, and are bad conductors of heat and elec- 
tricity. Some are commonly gaseous — oxygen, hydrogen, 
nitrogen, chlorine, and fluorine ; one fluid — bromine ; tlie 
others solid — carbon, phosphorus, sulphur, boron, selenium, 
and iodine. jThe metallic elements are, except mercury, 
solid at usual temperatures, have generally a metallic aspect, 
and are good conductors of heat and electricity. They are- 
divided into light and heavy metals, the former with a 



CHEMICAL PROPERTIES OP MINERALS. • 103 

specific gravity under 5, and a great affinity for oxygen, 
and again distinguished as either alkali-metals, potassium 
(or kaUum), sodium (or natrium'), lithium, barium, stron- 
tium, and calcium ; — or earth-metals, magnesium, lanthani- 
um, yttrium, glucinum, aluminium, zirconium, silicium. 
The heavy metals, with a specific gravity above 5, are 
divided into nohle^ which can be reduced or separated, from 
oxygen, by heat alone ; and ignoble^ whose affinity for 
oxygen renders them irreducible without other agents. 
Some of the latter are brittle and difficultly fusible, — tho- 
rium, titanium, tantalium (columbium), tungsten (wolfra- 
mium), molybdenum, vanadium, chromium, uranium, man- 
ganese, and cerium ; others are brittle and easily fusible or 
volatile — arsenic, antimony, tellurium, and bismuth ; and 
others malleable — zinc, cadmium, tin, lead, iron, cobalt, 
nickel, and copper. The noble metals are, — quicksilver, 
silver, gold, platinum, palladium, rhodium, iridium, and 
osmium. 

All the chemical combinations observed in the mineral 
kingdom follow the law of definite proportions ; that is, 
two elements always combine either in the same proportion, 
or so that the quantity of the one is multiplied by two, 
three, four, or some other definite number seldom very 
large. As the same law prevails throughout the whole 
range of elements, by assuming any one, usually hydrogen 
or oxygen, as unity or 1, and determining from experiment 
the simple proportion in which the others combine with it, 
a series of numbers is obtained which also expresses the 
proportions in which all these elements combine with each 
other. These numbers, therefore, mark the combining 
proportions or equivalents, as they are named, of the ele- 
ments. They are also named atomic weights, on the sup- 
position that matter consists of definite atoms, and that its 
combinations consist of one atom (or sometimes two atoms) 



104 A POPULAR TREATISE OX GEMS. 

of one substance, with one, two, three, or more atoms of 
another. This theory is not free from difficulties, but the 
language is often convenient. To designate the elements, 
chemists generally employ the first letter or letters of their 
Latin names. These signs also indicate one atom or 
equivalent of the element. Thus, O means oxygen in the 
proportion of one atom ; H, hydrogen in the same propor- 
tion ; N, an atom of nitrogen ; Na, an equivalent propor- 
tion of natrium or sodium. These signs and the equivalent 
weights are given in the table on next page, in one column 
of which hydrogen is taken as unity, in the other oxygen. 
The elements are arranged according to Berzelius, begin- 
ning with the most electro-positive, and ending with the 
most electro-negative. 

All these elements occur in minerals, but not more than 
twenty are common, and only about twelve abundant. 
They are also very rare in their simple or uncombined state ; 
only carbon in the diamond and graphite, sulphur, and 
about a dozen of the native metals, being thus known. 
More frequently minerals consist of two or more elements 
combined in accordance with those laws which prevail in 
inorganic compounds. The most important of these laws 
is that the combinations are binary ; that is, that the ele- 
ments unite in pairs, which may again unite either with 
another compound of two, or with a single element. Inor- 
ganic compounds also are generally distinguished from or- 
ganic by their greater simplicity. 



CHEMICAL PEOPERTIES OF MINERALS. 



105 



Table I. 
JEljements arranged in Electro- Chevnical order. 







Atomic "Weight.! 






Atomic Weight. 


Name. 


Sign. 






Name, 


Sign. 


*" 


H=:l 

39-2 


0=100. 

488-85 


H=l 


0=100. 


Potassium 


K 


Gluoinum 


G 


7 


86-5 


Sodium 


Na 


23-2 


290-9 


Aluminium . . . 


Al 


13-7 


*342-33 


Lithium 


Li 


7 


86-9 


Zirconium 


Zr 


22-5 


*840-4 


Ammonium. . . 


NH3 


17 




Thorium 


Th 


59-6 


744-90 


Barium 


Ba 


68-6 


856-88 


Cerium 


Ce 


46 


575 


Strontium 


Sr 


44 


547-28 


Lanthanium.. . 


La 


36? 


... 


Calcium 


Ca 


20 


251-5 


Didymium 


D 


... 


... 


Macjnesium . . . 


Ms: 


12-5 


154-0 


Uranium 


U 


60 


746 '36 


Yttrium 


Y 


32 


402-51 


Manganese 


Mn 


28 


345-89 


Iron 


Fe 

Ni 


28 
29 


850-53 
362-8 


Boron 

Titanium 


B - 
Ti 


11 
25 


136-2 

303-68 


Niekel 


Cobalt 


Co 


30 


375 


Tantalium 


Ta 


185 


1153-715 


Zinc 


Zn 
Cd 


32-2 
56 


406-59 
696-76 


Niobium 

Pelopium? 


Nb 
Pp 


... 




Cadmium 


Tin 


Sn 
Pb 


59 
104 


735-29 
1294-5 


Wolframium. . 
Molybdenum. 


W 
Mo 


92 

46 


1150-78 
575-83 


Lead 


Bismuth 


Bi 


208 


*2600 


Vanadium .... 


V 


66-6 


855-8 


Copper 


Cu 


31-7 


395-69 


Chromium 


Cr 


26-3 


328-59 


Mercury 


He: 


100 


1250 


Tellurium 


Te 


64 


802-12 


Silver 


Pd 


108 
53-3 


1349-66 
665-84 


Antimony. .... 
Arsenic 


Sb 

As 


122 

75 


1529 2 

*940-08 


Palladium; 


Rhodium 


Rh 


52 


651-4 


Phosphorus . . . 


P 


31 


*392-28 


Ruthenium 


Ru 


... 


... 


Nitrogen 


N 


14 


*l75-06 


Iridium 


Ir 


99 


1233-26 


Selenium ■. 


Se 


40 


494-58 


Platinum 


Pt 


99 


1233-26 


Sulphur 


S 


16 


200-75 


Osmium 


Os 


99 


1244-21 


lOxvgen 





8 


100 


Gold 


Au 
H 


168 
1 


*2458-83 
*12-48 


Iodine 

Bromine 


I 

Br 


126 

78-4 


n586 
*999-62 


Hydrogen 


Silicium 


Si] 


15 


tl87-5 


Chlorine 


CI 


36 


*443-28 


22-2 


J277-31 


Fluorine 


F 


18-7 


*233-80 


Carbon 


C 


6 


75-415 










* Double atoms 


. 






t L. Gmelin, w 


ho conside 


rs silica as composed of one 


atom base and two 


oxygen. 








X Berzelius. 









The above list includes ammonium, usually considered a 
compound body, and omits the two new metals, erbium 
and terbium. 

The following principles are observed in designating the 
combinations of these elementary substances : For those of 

5- 



108 A POPULAR TREATISE ON GEMS. 

the first order the signs of the two components are con- 
joined, and the number of atoms or equivalents of each ex- 
pressed by a number following the sign like an algebraic 
exponent. Thus, SO, SO^ SO^ are the combinations of 
one atom sulphur with one, two, and three atoms of oxygen ; 
FeS, FeS^, of one atom of iron with one or two of sulphur. 
But as combinations with oxygen and sulphur are very 
numerous in the mineral kingdom, Berzelius, to whom 
science is indebted for this system of signs, marks the atoms 
of oxygen by dots over the sign of the other element, and 
those of sulphur by an accent ; the above compounds being 
then designated thus^S, S, S, and Fef, Fe". In some cases 
two atoms of a base combine with three or five of oxygen 
or sulphur, as APO^, Fe'S'. In such cases Berzelius marks 
the double atom by a line drawn through the sign of the 
single atom ; thus, Al is two atoms aluminium Avith three 
of oxygen, or alumina ; -^-u, two of copper with one of oxy- 
gen, or oxide of copper. Where a number is prefixed to the 
sign like a coefficient in algebra, it includes both elements of 
the combination ; thus H is one atom water, 2 H two ; CaC 
is one atom carbonate of lime, 2 CaC two atoms, includ- 
ing, of course, two of calcium, two of carbon, and six of 
oxygen. 

The most common and important binary compounds are 
those with oxygen, contained in the following table, with 
their signs, atomic numbers, and amount of oxygen in 100 
parts. The more electro-negative are named acids, which 
are often soluble in water, and then render blue vegetable 
colors red. The more electro-positive are named oxides or 
bases, and show great aflinity or attractive power for the 
former. The most powerful are the alkaline bases, which 
are colorless and soluble in water ; less powerful are the 
earths, also colorless, but insoluble in water : 



Table II. — Binary Compounds 'wlth Oxijgen. 10' 



Name. 



Aluniiua 

Antimony oxide 

Antimonious acid 

Antiraonic acid 

Arsenious acid 

Arsenic acid 

Baryta , . . . . 

Bismuth peroxide 

Boiacic acid 

Carbonic acid 

Cerium protoxide 

" peroxide 

Chromium oxide ..,.,.... 

Chromic acid 

Cobalt protoxide 

Copper suboxide (red). .... 
" protoxide (black) . . 

Glucina ^ 

Iron protoxide 

" peroxide (red) 

'' proto-peroxide (blaclc) 

Lead protoxide 

Lime or Calcia 

Lithia 

Magnesia , 

Manganese protoxide 

'* peroxide 

"■ • proto-perox. (red) 

Molybdic acid 

Nickel protoxide 

Nitric acid » -. 

Phosphoric acid 

Potassa 

Silica (Gmelin) 

" (Berzelius) 

Soda 

Strontia 

Sulphuric acid 

Tantalic acid 

Thorina- 

Tni peroxide 

Titanic acid , 

Tungstic acid 

Uranium protoxide 

" peroxide 

Vanadic acid 

Water 

Yttria 

Zinc oxide 

Zirconia 



Sign. 



Al 

Sb 

si) 

Sb 
As 

As 
Ba 
Bi 

ii' 
c 

Gd 

Ce 

Cr 

"cV 
do 
Cw 

Cu 

g" 

Fe 

Fe 

Fe+in'e 

Pb 

Ca 

Li 

Mg . 

Mn 

Mil 

Mn+'iltl 

Mo 

Ni 

N* 

"PorP 

K 

Si 

Si* 

Na 

S'r 

S* 

fa 

Tb 

Sa 

fi 

W 

U 

IJ' 

V" 

H 

Za 
Zi— 'Zr 



Atomic WeiEfht. 



FI=:1. 0=100. 



51-4 
14G 

154 

162 

99 

115 

76-6 

232 

34-8 

22 

54 

116 

76-6 

50-3 

38 

71-4 

39-7 

38 

36 

80 

116 

112 

28 

15 

21 

86 

80 

116 

70 

37 

54 

71 

47-2 

31 

46-2 

31-2 

52 

40 

209 

67-6 

75 

41 

116 

68 

144 

92 

9 

40 

40-2 

30 4 



642-33 

1829-2 

1929-2 
2029-2 
1240-08 
1440-08 
956-88 
2900-00 
436-20 
2750 
674-72 
1449-39 
956-78 
628-39 
475 
891-39 
495-69 
490-05 
450-527 
1001-054 
1451-581 
1394-50 
351 -489 
186-9 
254-50 
445-89 
991-77 
1437-66 
875-83 
462-8 

675-06 

892-28 

688-856 

387-5 

577-31 

390-90 

647-29 

500-75 

2607-43 
844-90 
935-29 
503-68 

1450-78 
842-84 

1792-72 

1155 84 
112-48 
602-51 
506-59 
114-2 



Oxya;. 
in 100 
par ts. 

40-70 
16-40 

20-73 
24-64 

34-72 
10-45 
10-34 
68-78 
72-73 
14-82 
20 70 
31-35 
47-74 
21-05 
11-12 
20-17 
63-26 
22-19 
29-97 
26-08 
7-17 
28-45 
53-50 
39-30 
22-43 
30-25 
26-34 
34-28 
21-60 

7407 
56 04 
16-98 
51-61 
51-96 
25-68 
1645 
59-91 
11-51 
13-34 
21-38 
39-71 
20-67 
13-33 
1013 
26-19 
88-89 
19-90 
19-74 
26-37 



or 

II 

® 

II 



CD 

O 

03 



o 

.3 

a; 

f-i 



O 

4-> 

O 



4J 






H 
O 



108 A POPULAR TREATISE ON GEMS. 

Similar to the compounds of oxygen are those with sul- 
phur, usually named sulphurets, and considered analogovis 
to the oxidized bases. A few of more electro-negative 
character, resembling acids, have been distinguished as sul- 
phides. Some other compounds have been named haloid 
salts, and consist of certain electro-negative elements, com- 
bined with electro-positive ones, as bases. 

Many of these combinations occur as independent sj^ecies 
in the mineral kingdom, especially those with oxygen and 
sulphur. Thus the most abundant of all minerals, quartz, 
is an oxide, and corundum is of similar nature. Many 
oxides of the heavy metals, as of iron, tin, copper, and anti- 
mony; and some suj^er-oxides, as of lead and manganese 
(pyrolusite), are very common. Compounjcls with sulphur 
also abound, either as sulphides, with the character of 
acids, like realgar, orpiment, and stibine ; or as sulphurets, 
resembling bases, like galena, argentite, and pyrite. Less 
frequent are haloid salts, with chlorine and fluorine, as 
common salt and fluor spar; and still rarer those with 
iodine and bromine. On the other hand, metallic alloys, 
or combinations of electro-negative with electro-positive 
metals, are far from uncommon, especially those with 
arsenic, tellurium, or antimony. 

Combinations of these binary compounds with each other 
are still more common, the greater number of minerals 
being composed of an acid and base. By far the greater 
number are oxygen-salts, distinguished by giving to the 
acid the termination ate ; thus sulphate of lead, silicate of 
lime, and in like manner numerous carbonates, phosphates, 
arseniates, aluminates. The sulphur-salts {two metals com- 
bined with sulphur, and these again combined with each 
other) "are next in number, and perform a most important 
part in the mineral kingdom. The hydrates, or combina- 
tions of an oxide with water, are also common, and much 



CHEMICAL PROPERTIES OF MINERALS. 109 

resemble the oxygen salts, the water sometimes acting as 
an electro-positive, at other times as an electro-negative 
element. Combinations of a higher order are likewise 
common, especially the double salts, or the union of two 
salts into a new body ; and even these again with water, 
as alum and many hydrous silicates. The chemical formulae 
for these compound salts are formed by writing the signs 
of the simple salts with the sign of addition between them : 
thus Ca C-f Mg C, i. e., carbonate of lime and carbonate of 
magnesia, or brown spar ; Al Si^ -f K Si^ or orthoclase ; 
3 Na F -f AP F^, or cryolite, composed of three conipound 
atoms of fluorine and sodium united to one compound atom, 
consisting of three of fluorine and two of aluminium. 

Influence of the CJiemical Composition on the External 
Characters of Minerals. 

That the characters of the compound must in some way 
or other depend on those of its component elements, seems, 
as a general proposition, to admit of no doubt. Hence it 
might be supposed possible, from a know^ledge of the com- 
position of a mineral, to draw conclusions in reference to 
its form and other properties ; but practically this has not 
yet been effected. The distinction between the mineral- 
izing and mineralizable, or the forming and formed, ele- 
ments, lies at the foundation of all such inquiries. Certain 
elements in a compound apparently exert more than an 
eqilal share of influence in determining its physical prop- 
erties. Thus the more important non-metallic elements, 
as oxygen, sulphur, chlorine, fluorine, are remarkable for 
the influence they exert on the character of the compound. 
The sulphurets, for example, have more similarity among 
themselves than the various compounds of one and the 
same metal with the non-metallic bodies. Still more gen- 



110 A POPULAR TREATISE OX GEMS. . 

erally it would appear that the electro-negative element in 
the compound is the most influential, or exerts the greatest 
degree of active forming power. After the non-metallic 
elements the brittle, easily fusible metala. rank next in 
power; then the ductile . ignoble metals; then the noble 
metals ; then the brittle, difficultly fusible ; and last of all, 
the metals of the earths and alkalies. 

It is sometimes stated that each particular substance can 
crystallize only in one particular form or series of forms. 
This is, however, only partially true ; and sulphur, for in- 
stance, which usually crystallizes in the rhombic system, 
when melted may form monoclinohedric crystals. This 
property is named dimorphisni ; and hence the same chem- 
ical substance may form two, or even more distinct bodies 
or mineral species. Thus carbon in one form is the dia- 
mond, in another graphite ; carbonate of lime appears as 
calc-spar or arragonite ; the bisulphuret of iron, as pyrite 
and marcasite. An example of trimorphism occurs in the 
titanic acid, forming the three distinct species, anatase, 
rutile, and brookite. Even the temperature at which a 
substance crystallizes influences its forms, and so far its 
composition, as seen in arragonite, Glauber salt, natron,' 
and borax. 

Still more important is the doctrine of isomorjyhisni^ des- 
ignating the fact that two or more simple or compound 
substances crystallize in one and the same form ; or often 
in forms which, though not identical, yet approximate very 
closely. This similarity of form is generally combined with 
a similarity in other physical properties. Among minerals 
that crystallize in the tesseral form, isomorphism is of course 
common and perfect, there being no diversity in the dimen- 
sions of the primary form ; but for this very reason it is of 
less interest. It is of more importance among mono-axial 
crystals, the various series of which are separated from each 



CHEMICAL PEOPEETIES OF MINERALS. Ill 

other by differences in the proportion of the primary form. 
In these, perfect identity is seldom observed, but only very 
great similarity. 

The more iip.portant isomorphic substances are the fol- 
lowing : 

I. Simple substances: 

(1.) Fluorine and chlorine. 

(2.) Sulphur and selenium. 

(3.) Arsenic, antimony, tellurium. 

(4.) Cobalt, iron, nickel. 

(5.) Copper, silver, quicksilver, gold (?). 

II. Combinations with oxygen : 
(1.) Of the formula R. 

{a.) Lime, magnesia, protoxide of iron, protoxide 
of manganese, oxide of zinc, oxide of nickel, 
oxide of cobalt, j)otassa, soda. . 
(b.) Lime, baryta, strontia, lead-oxide. 
(2.) Of the formula U. 

(a.) Alumina, peroxide of iron, peroxide of manga- 
nese, oxide of chromium. 
{b.) Antimony oxide, arsenious acid. 
(3.) Formula R. Tin-oxide, titanium-oxide. 

(4.) Formula R. Phosphoric acid, arsenic acid. 
(5.) Formula *R. 

[a.) Sulphuric acid, selenic acid, chromic acid, man- 
ganese acid. 

[b.) Tungstic acid, molybdic acid. 

III. Combinations with sulphur : 

(1.) Formula R'. Sulphuret of iron Fe', and sulphu- 
ret of zinc Zn'. 

(2.) Formula ih'". Sulphuret of antimony -Sb'", and 
sulphuret of Arsenic As'". 

(3.) Formula i?:'. Sulphuret of copper -0u', and sul- 
phuret of silver Ag'. 



112 A POPULAR TREATISE ON GEMS. 

These substances are named vicarious, from the singular 
property that in chemical compounds they can mutually 
replace each other in indefinite proportions, and very often 
without producing any important change in the form or 
other physical properties. But there are numerous in- 
stances among the silicates, where the mutual replacement 
of the isomorphic bodies, especially when the oxides of the 
heavy metals come in the room of the earths and alkalies, 
exerts a most essential influence on the external aspect of 
the species, particularly in regard to color, specific gravity, 
and transparency. The varieties of hornblende, augite, 
garnet, epidote, and many other minerals, are remarkable 
proofs of this influence. This intermixture of isomorphic 
elements confers many valuable properties on minerals, and 
to it this department of nature owes much of its variety and 
beauty. Without the occasional presence of the coloring- 
substances, especially the oxides of iron and manganese, 
the non-metallic combinations would have exhibited a very 
monotonous aspect. It is also remarkable, that in some 
silicates the substitution of a certain portion of the metallic 
oxides for the earthy bases seems to be almost a regular 
occurrence; while in others, as the felspars and zeolites, 
this rarely happens. This fact is of very great economic 
importance, as drawing attention to important elements 
often combined wath others of less value. Thus iron oxide 
and chrome oxide, sulphuret of copper and sulphuret of 
silver, nickel and cobalt, may be looked for in connection. 
The general chemical formula for such compounds is^ formed 
by writing R (= radicle or basis) for the whole isomorphic 
elements ; and in special instances to place their signs 
either one below the other, connected by a bracket, or, as 
is more convenient, to inclose them in brackets one after 
the other, separated by a comma. Thus the general sign 
for the garnet is R^ Si^+R Si, which, when fully expressed, 



CHEMICAL PROPERTIES OP MINERALS. 113 

9-'] .. M y.. . . '. 

becomes Pe" ^Si'+5 [ Si; or(CaSlV,Mn')Si'+(Al,*;e)Si, 

and the mineral forms many varieties, as the one or other 
element predominates. 

Chemical Heaction of Minerals. 

The object of the chemical examination of minerals is 
the discovery of those elementary substances of which they 
consist. This examination is named qualitative when the 
natm*e of the elements alone, quantitative when also their 
relative amount, is sought to be determined. Mineralogists 
are in general content with such an examination as will 
discover the more important elements, and which can be 
carried on with a simple apparatus, and small quantities of 
the substance investigated. The indications thus furnished 
of the true character of the mineral are, however, frequently 
of high importance. Two methods of testing minerals are 
employed, the one by heat chiefly applied through the blow- 
pipe, the second by acids and other reagents in solution. 

Use of the blowpipe. 

The blowpipe in its simplest form is merely a conical 
tube of brass or other metal, curved round at the smaller 
extremity, and terminating in a minute circular aperture 
not larger than a fine needle. Other forms have been 
proposed, one of the most useful being a cone of tin, open 
for the application of the mouth at the smaller end, and 
with a brass or platina beak projecting from the side near 
the other or broad end. With this instrument a stream of 
air is conveyed from the mouth to the flame of a lamp or 
candle, so that this can be turned aside, concentrated, and 



114 A POPULAR TREATISE ON GEMS. 

directed upon any small object. The flame thus acted on 
consists of two parts — the one nearest the beak of the blow- 
pipe forming a blue obscure cone, the other external to this 
being of a shining yellow or reddish-yellow color. The 
blue cone consists of the inflammable gases not yet fully 
incandescent, and the greatest heat is just beyond its point, 
where this is fully efiected. The blue flame still needs 
oxygen for its support, and consequently tends to withdraw 
it from any body placed within its influence, and is named 
the reducing flame. At the extremity of the yellow cone, 
on the other hand, the whole gases being consumed and 
the external air having free access, bodies are combined 
with oxygen, and this part is named the oxidating flame. 
Their action being so distinct, it is of great importance for 
the student to learn to distinguish accurately these two 
portions of the flame. This is best done by experimenting 
on a piece of metallic tin, which can only be kept pure in a 
good reducing flame, and acquires a white crust when acted 
on by the oxidating flame. 

The portion of the mineral to be examined should not 
be larger than a peppercorn, or a fine splinter a line or two 
long. It is supported in the flame either by a pair of fine 
pincers pointed with platinum, or on slips of platinum-foil, 
or on charcoal. Platinum is best for the siliceous minerals, 
whereas for metallic substances charcoal must be employed. 
For this purpose solid uniform pieces are chosen, and a 
small cavity formed in the surface in which the mineral to 
be tested can be deposited. 

In examining a mineral by heat, it should be first tested 
alone, and then with various reagents. When placed alone 
in a matrass or tube of glass closed at one end, and heated 
over a spirit-lamp, water or other volatile ingredients, mer- 
cury, arsenic, tellurium, often sulphur, may readily be de- 
tected, being deposited in the cooler part of the tube, or, 



J 



CHEMICAL PROPERTIES OF MINERALS. 115 

like fluorine, acting on the glass. It may next be tried in 
an open tube of glass, through which a more or less strong 
current of air passes according to the inclination at which 
the tube is held, so that volatile oxides or acids may be 
formed ; and in this way the chief combinations of sulphur, 
selenium, tellurium^ and arsenic are detected. On char- 
coal, in the reducing flame, arsenic, and in the oxidating 
flame, selenium or sulphur, are shown by their peculiar 
odor ; antimony, zinc, lead, and bismuth leave a mark or 
colored ring on the charcoal ; and other oxides and sul- 
phurets are reduced to tlie pure metal. On charcoal or in 
the platinum pincers the fusibility of minerals' is tested, and 
some other phenomena should be observed — as whether 
they intumesce (bubble up), efiervesce, give out fumes, be- 
come shining, or impart a color to the flame. The color is 
seen when the assay is heated at the point of the inner 
flame, and is — 

Keddish-yellow, from soda and its salts ; 

Violet, from potash and most of its salts ; 

Eed, from lithia, strontia, and lime ; 

Green, from baryta, phosphoric acid, boracic acid, molybdic acid, 

copper oxide, and tellurium oxide ; 
Blue, from chloride of copper, bromide of copper, selenium, arsenic, 

antimony, and lead. 

The fusibility, or ease with which a mineral is melted, 
should also be observed; and to render this character more 
precise, Yon Kobell has proposed this scale: — (l,) Anti- 
mony glance, which melts readily in the mere candle flame ; 
(2.) Natrolite, which in fine needles also melts in the candle 
flame, and in large pieces readily before the blowpipe ; (3.) 
Almandine (garnet from Zillerthal), which does not melt 
in the candle flame even in fine splinters, but in large pieces 
before the blowpipe ; (4.) Strahlstein (hornblende from 
Zillerthal) melts with some difliculty, but still more readily 
than (5.) Orthoclase (or adularia felspar); and (6.) Bron- 



116 A POPULAE TREATISE ON GEMS. 

zite or cliallage, of which only the finest fibres can be 
rounded by the blowpipe. In employing this scale, fine 
fragments of the test minerals and of that to be tried, and 
nearly of equal size, should be exposed at the same time to 
the flame. A more common mode of expressing fusibility 
is to state whether it is observable in large or small grains, 
in fine splinters, or only on sharp angles. The result or 
product of fusion also yields important characters, being 
sometimes a glass, clear, opaque, or colored ; at other times 
an enamel, or a mere slag. 

The most important reagents for testing minerals with 
the blowpipe are the following: (1.) Soda (the carbonate), 
acting as a flux for quartz and many silicates, and especially 
for reducing the metallic oxides. For the latter purpose, 
the assay (or mineral to be tried) is reduced to powder, 
kneaded up with moist soda into a small ball, and placed 
in, a cavity of the charcoal. Very often both the soda and 
assay sink into the charcoal, but by continuing the opera- 
tion they either again appear on the surface, or, when it is 
completed, the charcoal containing the mass is finely pounded 
and washed away with water, w^henthe reduced metal is 
found in the bottom of the vessel. (2.) Borax (biborate of 
soda) serves as a flux for many minerals, which are best 
fused in small splinters on platina wire. The borax w^hen 
first exposed to the flame swells up or intumesces greatly, 
and it should therefore be first melted into a small bead, in 
which the assay is placed. During the process the student 
should observe w^hether the assay melts easily or difficultly, 
with or without eflervescence, what color it imparts to the 
product both when warm and w^hen cold, and also the eftect 
both of the oxidating and reducing flames. (3.) Microcos- 
mic salt, or salt of phosphorus (phosj^hate of soda and am- 
monia), is specially important as a test for metallic oxides, 
which exhibit far more decided colors with it than with 



CHEMICAL PROPERTIES OF MINERALS. 117 

borax. It is also a useful reagent for many silicates, whose 
silica is separated from the base and remains undissolved 
in the melted salt. (4.) Solution of cobalt (nitrate of co- 
balt dissolved in water), or dry oxalate of cobalt, serve as 
tests of alumina, magnesia, and zinc oxide. 

In examining minerals in the moist way, the first point 
to be considered is their solubility, of which three degrees 
may be noted: (l) minerals soluble in water; (2) minerals 
soluble in hydrochloric or nitric acid; and (3) those un- 
affected by any of these fluids. The minerals soluble in 
water are either acids (almost only the boracic acid or sas- 
solin and the arsenious acid), or oxygen or haloid salts. 
These are easily tested, one part of the solution being em- 
ployed to find the electro-positive element or basis, the 
other the electro-negative or acid. 

Minerals insoluble in water may next be tested with the 
above acids; the nitric acid being preferable when it is 
probable, from the aspect of the mineral or its conduct be- 
fore the blowpipe, that it contains an alloy, a sulphuret, 
or arseniate of some metal. In this manner the carbonic, 
phosphoric, arsenic, and chromic acid salts, many hydrous 
and anhydrous silicates, many sulphurets, arseniates, and 
other metallic compounds, are dissolved, so that further 
tests may be employed. 

The minerals insoluble either in water or these acids are 
sulphur, graphite, cinnabar, some metallic oxides, some 
sulphates, and compounds with chlorine and fluorine, and 
especially quartz, and various siUcates. For many of these 
no test is required, or those furnished by the blowpipe are 
sufficient. The silicates and others may be fused with four 
times their weight of anhydrous carbonate of soda when 
they are rendered soluble, so that further tests may be ap- 
plied. 



118 A POPULAR TREATISE OX GEMS. 

Chemical Reaction of the more Important Eleinents. 

It is not intended in this place to describe the chemical 
nature of the elementary substances, and still less to enu- 
merate the whole of those marks by which the chemist can 
detect their presence. Our object is limited principally to 
the conduct of minerals before the blowpipe, and to a few 
simple tests by which their more important constituents 
may be discovered by the student. 

I. NON-METALLIC ELEMENTS, AND THEIR COMBINATIONS 

WITH OXYGEN. 

Nitric Acid. — Most of its salts detonate when heated on 
charcoal. In the closed tube they form nitrous acid, easily 
known by its orange color and smell ; a test more clearly 
exhibited when the salt is mixed with copper filings and 
treated with concentrated sulphuric acid. When to the 
solution of a nitrate, a fourth part of sulphuric acid is added, 
and a fragment of green vitriol placed in it, the surround- 
ino; fluid becomes of a dark-brown color. 

Sulphur and its compounds, in the glass tube or on char- 
coal, form sulphurous acid, easily known by its smell. The 
minutest amount of sulphur or sulphuric acid may be de- 
tected by melting the pulverized assay with two parts soda 
and one part borax, and placing the bead moistened with 
water on a plate of clean silver, which is then stained brown 
or black. Solutions of sulphuric acid give with chloride of 
barium a heavy white precipitate, insoluble in acids. 

Phosphoric Acid. — Most combinations with this acid 
tinge the blowpipe flame green, especially if previously 
moistened with sulphuric acid. The experiment must be 
performed in the dark, when even three per cent, of the 
acid may be detected. If the assay is melted with six parts 



CHEMICAL PBOPERTIES OF MINERALS. 119 

of soda, digested in water, filtered, and neutralized with 
acetic acid, the solution forms an orange-yellow layer round 
a crystal of nitrate of silver. This solution, with muriate, 
of magnesia, forms a. white crystalline precipitate. 

Selenhan and Selenic Acid are readily detected by the 
strong smell of decayed horse-radish, and leave a gray de- 
posit with a metallic lustre on the charcoal. 

Chlorine and its salts. When oxide of copper is melted 
with salt of phosphorus into a very dark-green bead, and 
an assay containing chlorine fused with this, the flame is 
tinged of a beautiful reddish-blue color, till all the chlorine 
is driven off. If very little chlorine is present, the assay is 
dissolved in nitric acid (if not soluble it must first be melted 
with soda on platinum wire), and the diluted solution gives, 
with nitrate of silver, a precipitate of chloride of silver, 
which is first white, but on exposure to the light becomes 
gradually brown, and at length black. 

Iodine and its salts, treated like chlorine, imj)art a very 
beautiful bright-green color to the flame ; and heated in 
the closed tube with sulphate of potash, yield violet-colored 
vapors. In solution it gives, with nitrate of silver, a pre- 
cipitate similar to chlorine, but which is very diflicultly 
soluble in ammonia. Its surest test is the blue color it im- 
parts to starch, best seen by pouring concentrated sul- 
phuric acid over the mineral in a test tube which has a 
piece of paper or cotton covered with moist starch over its 
mouth. 

Bromine and its salts, treated in the same manner with 
salt of phosphorus and oxide of copper, color the blowpipe 
flame greenish-blue. In the closed tube with nitrate of 
potassa they yield bromine vapors, known by their yellow 
color and peculiar disagreeable smell. Treated with sul- 
phuric acid, bromine in a i(d\N hours colors starch pome- 
granate-yellow. 



120 A POPULAR TREATISE- ON GEMS. 

Fluorine is shown by heating the assay with snlj^hate of 
potassa, in a closed tube with a strip of logwood-paper in 
,the open end. The paper becomes straw-yellow, and the 
glass is corroded. Another test is to heat the pulverized 
mineral with concentrated sulphuric acid in a shallow dish 
of platinum (or lead), over which a plate of glass covered 
with a coat of wax, through which lines have been drawn 
with a piece of sharp-pointed wood, is placed. If fluorine 
is present, the glass is etched where exposed. 

Boracic Acid. — The mineral alone. Or moistened with 
sulphuric acid, when melting, colors the flame momentarily 
green. If the assay be heated with sulphuric acid, and 
alcohol added and set on fire, the flame is colored green 
from the vapors of the boracic acid. 

Carho7i^ pulverized and heated with saltpetre, detonates, 
leaving carbonate of potassa. Carbonic acid is not easily 
discovered with the blowpipe, but the minerals containing 
it effervesce in hydrochloric acid, and the colorless gas 
that escapes renders litmus-j^aper red. In solution it forms 
a precipitate with lime-water, which is again dissolved with 
effervescence in acids. 

Silica., before the blowpipe, alone is unchanged ; is very 
slowly acted on by borax, very little by salt of phosphorus, 
but with soda melts entirely with a brisk effervescence into 
a clear glass. The silicates are decomposed by salt of 
phosphorus, the silica being left in the bead as a powder 
or a skeleton. Most of them melt with soda to a trans- 
parent glass. Some silicates are dissolved in hydrochloric 
acid, and this the more readily the more powerful the 
basis, the less pi'oportion of silica, and the greater the 
amount of water they contain. Sometimes the acid only 
extracts the basis, leaving the silica as a powder or jelly ; 
or the silica too is dissolved, and only gelatinizes on evapo- 
ration. The insoluble silicates may be first melted with 

i 



CHEMICAL PEOPERTIES OF MINERALS. 121 

some carbonate of an alkali, when the solution gelatinizes, 
and finally leaves a dry residuum, of which the part insolu- 
ble in warm hydrochloric acid has all the properties of 
silica. 

II. THE ALKALIES AND EARTHS. 

Ammonia^ heated with soda in a closed tube, is readily 
known by its smell. Its salts, heated with solution of 
potassa, also yield the vapor, known from its smell, its 
action on turmeric-paper, and the white fumes that rise 
from a glass tube dipped in hydrochloric acid held over it. 

Soda^ imparts a reddish-yellow color to the external 
flame when the assay is fused or kept at a strong red heat. 
In solution it yields no precipitate with chloride of plati- 
num or sulphate of alumina. 

JLithia is best recognized by the beautiful carmine-red 
color it imparts to the flame during the fusion of a mineral 
containing it in considerable amount. Where the propor- 
tion is small, the color appears if the assay be mixed with 
1 part fluor spar and \^ parts sulphate of potassa. In 
concentrated solutions it forms a precipitate with the phos- 
phate and carbonate of soda, but none with bichloride of 
platinum, sulphate of alumina, or acetic acid. 

Potassa gives a violet color to the external cone, when 
the assay is heated at the extremity of the oxidating flame. 
The- presence of lithia or soda, however, disturbs this re- 
action. It may still be discovered by melting the assay in 
borax glass colored brown by nickel oxide, which is 
changed to blue by the potassa. In concentrated solutions 
of potassa, the bichloride of platinum gives a citron-yellow 
precipitate ; acetic acid, a white granular precipitate ; and 
sulphate of alumina, after some time, a deposit of alum- 
crystals. 

Baryta. — The carbonate of this earth melts easily to a 

G 



122 A POPULAR TREATISE ON GEMS. 

clear glass, milk-white when cold; the sulphate is very 
difficultly fasible. Both strongly heated at the point of 
the blue flame impart a green tinge to the outer flame. 
When combined with silica it cannot be well discovered by 
the blowpipe. In solution, salts of baryta yield, with sul- 
phuric acid or solution of sulphate of lime, immediately a 
fine white precipitate insoluble in acids or alkalies. 

Strqntia^ the carbonate, even in thin plates, only melts 
on the edges, and forms cauliflower-like projections of 
dazzling brightness ; the sulphate melts easily in the oxi- 
dating flame, and in the reducing flame is changed into 
sulphuret of strontium, which, dissolved in hydrochloric 
acid, and evaporated to dryness, gives a fine carmine-red 
color to the flame of alcohol. Strontia in solution gives 
a precipitate with sulphuric acid, or with sulphate of lime, 
but not hnniediately. 

Lime. — The carbonate is rendered caustic by heat, when 
it has alkaline properties, and' readily absorbs water. The 
sulphate in the reducing flame changes to the sulphuret 
of calcium, which is also alkaline. Sulphuric acid precipi- 
tates lime only from very concentrated solutions; oxalic 
acid even from very weak ones ; and silico-hydrofluoric acid 
not at all. As baryta and strontia also form precipitates 
with the first two reagents, they must previously be sepa- 
rated by sulphate of potassa. Chloride of calcium tinges 
the flame of alcohol yellowish-red. 

Magnesia^ alone, or as a hydrate, a carbonate, and in 
some other combinations, when ignited with solution of 
cobalt, or the oxalate of cobalt, assumes a light-red tint. 
It is not precipitated from a solution either by sulphuric 
acid, oxalic acid, or silico-hydrofluoric acid ; but phosphoric 
acid, with ammonia, throws down a white crystalline pre- 
cipitate of phosphate of ammonia and magnesia. 

Alumjina alone is infusible. In many combinations, when 



CHEMICAL PEOPERTIES OF MINEEALS. 123 

ignited with solution of cobalt, it assumes a fine blue color. 
It is thrown down by potassa or soda as a white volumin- 
ous precipitate, which in excess of the alkali is easily and 
completely soluble, but is again precipitated by muriate of 
ammonia. Carbonate of ammonia also produces a precipi- 
tate which is not soluble in excess. 

Glucina^ Yttria^ Zirconia^ and Tliorina are not prop- 
erly distinguished by blowpipe tests, though the minerals 
in which they occur are well marked in this way. In- 
solution, glucina acts wdth potassa like alumina; but the 
precipitate wdth carbonate of ammonia is again soluble, 
with excess of the alkali, and the two earths may thus be 
separated. Yttria is precipitated by potassa, but is not 
again dissolved by excess of the alkali. With carbonate 
of ammonia it acts like glucina. It must be observed, 
however, that the substance formerly named yttria is now 
considered a mixture of this earth with the oxides of er- 
bium, terbium, and lanthanium. Zirconia acts with potassa 
like yttria, and Avith carbonate of ammonia like glucina. 
Concentrated sulphate of potassa throws down a double salt 
of zirconia and potassa, which is very little soluble in 23ure 
water. 

III. THE METALS. 

Arsenic and its sulphuret on charcoal yield fumes, with 
a smell like garlic, and 'sublime in the closed tube. The 
greater numjber of alloys of arsenic in the reducing flame 
leave a white deposit on the charcoal ; or, where it is in 
larger proportion, give out grayish-white fumes with a 
smell of garlic. Some alloys also yield metallic arsenic in 
the closed tube. In the open tube all of them yield arse- 
nious acid, and those containing sulphur also sulphurous 
fumes. Many arsenic acid salts emit evident odors of 
arsenic when heated on charcoal with soda ; and some sub- 



124 A POPULAR TREATISE OX GEMS. 

lime metallic arsenic when heated with pulverized charcoal 
in the closed tube. 

Anthnony melts easily on charcoal, emitting dense white 
fumes, and leaving a ring of white crystalline oxide on the 
support. In the closed tube it does not sublime, but burns 
in the open tube with white smoke, leaving a sublimate on 
the glass, which is easily driven from place to place by heat. • 
Most of its compounds, with sulphur or with the other 
metals, show similar reaction. Antimony oxide on char- 
coal melts easily, fumes, and is reduced, coloring the flame 
pale greenish-blue. 

Bismuth melts easily, fumes, and leaves a yellow oxide 
on the charcoal. In the closed tube it does not sublime, 
and in the open tube scarcely fumes, but is surrounded by 
the fused oxide, dark-brown when warm, and bright-yellow 
when cold. Its oxides are easily reduced. A great addi- 
tion of water produces a white precipitate from its solution 
in nitric acid. 

Tellurium fumes on charcoal, and bec(Jmes surrounded 
by a white mark with a reddish border, which, when the 
reducing flame is turned on it, disappears with a bluish- 
green light. In the closed tube tellurium gives a subli- 
mate of the gray metal ; and in the open tube produces 
copious fumes, and a white powder which can be melted 
into small clear drops. 

Mercury in all its combinations is volatile, and yields a 
metallic sublimate when heated alone, or with ..tin or soda 
in the closed tube. 

Zinc, when heated with soda on charcoal, forms a de- 
posit, which, when warm, is yellow ; when cold, white ; is 
tinged of a fine green by solution of cobalt, and is not far- 
ther volatile in the oxidating flame. In solution, zinc is 
precipitated by potassa as a white gelatinous hydrate, easily 
redissolved in the excess of the alkali. 



CHEMICAL PKOPERTIES OF MINERALS. 125 

Tin forms a white deposit on the charcoal behind the 
assay, which takes a bluish-green color with the solution of 
cobalt. The oxide is easily reduced by soda. 

Lead forms a sulphur-yellow deposit with a white border 
on the charcoal when heated in the oxidating flame, and 
with soda is easily reduced. The solutions of its salts are 
colorless, but give a black precipitate with sulphuretted 
hydrogen ; with sulphuric acid a white, and with chroraate 
of potassa a yellow, precipitate. 

Cadmium produces, with soda, a reddish-brown or 
orange-yellow ring, with iridescent border on the charcoal, 
and also on platinum-foil. 

Manganese alone, melted with borax or salt of phos- 
phorus on the platinum wire in the oxidating flame, forms 
a fine amethystine glass, which becomes colorless in the 
reducing flame. In combination with other metals, the 
pulverized assay mixed with two or three times as much 
soda, and melted in the oxidating flame on platinum -foil, 
forms a bluish-green glass. Potassa or ammonia throws 
down from solutions of its salts a white hydrate, which, in 
the air, becomes gradually dark-brown. 

Cobalt^ melted with borax in the oxidating flame, gives 
a beautiful blue glass. Minerals of metalHc aspect must be 
first roasted on charcoal. The salts of protoxide of cobalt 
form bright-red solutions, from which potassa throws down 
a blue flaky hydrate, which becomes olive-green in the air. 

Nickel^ the assay, first roasted in the open tube and on 
charcoal, produces in the oxidating flame, with borax, a 
glass, which hot, is reddish or violet brown ; when cold, 
yellowish or dark red ; and by the addition of saltpetre, 
changes to blue. In the reducing flame the glass appears 
gray. With salt of phosphorus the reaction is similar, but 
the glass is almost colorless when cold. The salts in solu- 
tion have a bright-green color, and with potassa, form a 



126 A POPULAR TREATISE ON GEMS. 

green precipitate of hydrated nickel-oxide, which is un- 
changed in the air. 

Copper may in most cases be discovered by melting 
the assay (if apparently metallic, iirst roasted) with boi'ax 
or salt of phosphorus in the oxidating flame, when an 
opaque reddish-brown glass is produced, a small addition 
of tin aiding in the result. In the reducing flame, the glass, 
when warm, is green ; when cold, blue. With soda, me- 
tallic copper is produced. A small proportion of copper 
may often be detected by heating the assay, moistened 
with hydrochloric acid, in the oxidating flame, which is 
then tinged of a beautiful green color. Solutions of- its 
salts are blue or green, and produce a brownish-black pre- 
cipitate, with sulphuretted hydrogen. Ammonia at first 
throws down a pale-green or blue precipitate, but in excess 
produces a very fine blue color. 

Silver in the metallic state is at once known, and from 
many combinations can be readily extracted on charcoal 
with soda. From its solution in nitric acid, silver is thrown 
down by hydrochloric acid as a white chloride, which in 
the light soon becomes black, is soluble in ammonia, and 
can again be precipitated from this solution by nitric acid 
as chloride of silver. 

Gold^ when pui-e, is readily knoTvm, and is easily separated 
from its combinations with tellurium on charcoal. If the 
grain is white, it contains more silver than gold, and must 
then be heated in a porcelain capsule with nitric acid, which 
gives it a black color, and gradually removes the silver, if 
the gold is only a fourth part or less. If the proportion of 
gold is greater, the nitro-cliloric acid must be used, which, 
then removes the gold. From its solution in this acid the 
protochloride of tin throws down a purple precipitate (p>ur- 
ple of Cassius), and the sulphate of iron, metallic gold. 

JPlatinum, and the metals usually foupd with it, cannot 



CHEMICAL PEOPERTIES OF MINERALS. 127 

be separated from each other by heat. Only the Osmium- 
iridhmi strongly heated m the closed tube with saltpetre 
is decomposed, forming osmium acid, known from its pecu- 
liar pungent odor. The usual mixture of platinum grains 
is soluble in nitro-chloric acid, leaving osmium-iridium. 
From this solution the platimiin is thrown down by sal- 
ammonia as a double chloride of platinum and ammonium. 
From the solution evaporated, and again diluted, with 
cyanide of mercury, the palladium separates as cyanide of 
palladium. The rhodium may be separated by its property 
of combining with fused bisulphate of potassa, which is not 
the case with platinum or iridium. 

Cerium^ when no iron-oxide is pi'^sent,^ produces, with 
borax and salt of phosphorus, in the oxidating flame, a red 
or dark-yellow glass, which becomes very pale when cold, 
and colorless in the reducing flame. Lanthanium oxide 
forms a white colorless glass ; didymium^ a dark amethyst- 
ine glass. 

Iron^ the peroxide and hydrated peroxide, become black 
and magnetic before tlie blowpipe, and form, with borax or 
salt of phosphorus, in the oxidating flame, a dark-red glass, 
becoming bright-yellow when cold; and in the reducing 
flame, especially on adding tin, an olive-green or mountain- 
green glass. The peroxide colors a bead of borax contain- 
ing copper oxide, bluish-green ; the protoxide produces red 
spots. Salts of protoxide of iron form a green solution, 
from which potassa or ammonia throws down the protoxide 
as a hydrate, which is first white, then dirty-green, and 
finally yellowish-brown. Carbonate of lime j)roduces no 
precipitate. The salts of the peroxide, on the other hand, 
form yellow solutions from which the peroxide is thrown 
down by potassa or ammonia as a flaky-brown hydrate. 
Carbonate, of lime also causes a precipitate. 

Chromium forms, with borax or salt of phosphorus, a 



128 A POPULAR TKEATISE ON GEMS. 

glass, fine emerald-green when cold, though when hot often 
yellowish or reddish. Its solutions are usually green, and 
the metal is thrown down by potassa as a bluish-green hy- 
drate, again dissolved in excess of the alkaU. The chrome 
in many minerals is very certainly discovered by melting 
the assay with three times its bulk of saltpetre, which, dis- 
solved in water, gives with acetate of lead a yellow precipitate. 

Vanadium, melted on platinum wire with borax or salt 
of phosphorus, gives a fine green glass in the reducing 
flame, which becomes yellow or brown in the oxidating 
flame, distinguishing it from chrome. 

Uranium, with salt of phosphorus, forms in the oxidating 
flame a clear yellow ; in the reducing flame a fine green 
glass. With borax its reaction is similar to that of iron. 

Molyhdenum forms in the reducing flame, with salt of 
phosphorus, a green ; with borax, a brown, glass. 

Tungsten or W^olfram forms, with salt of phosphorus, in 
the oxidating flame, a colorless or yellow, in the reducing 
flame, a very beautiful blue glass, which appears green 
when warm. When accompanied by iron, the glass is blood- 
red, not blue. Or melt the assay with five times as much 
soda in a platinum spoon, dissolve it in water, filter, and 
decompose the result with hydrochloric acid, which throws 
do.wn the tungstic acid, which is white when cold, but 
citron-yellow when heated. 

Tantaliiim,, as tantalic acid, is readily dissolved by salt 
of phosphorus, and in large quantity into a colorless glass, 
which does not become opaque in cooling, and does not 
acquire a blue color from solution of cobalt. Or fuse the 
assay with two times as much saltpetre, and three times as 
much soda, in a platinum spoon ; dissolve this, filter, and 
decompose the fluid by hydrochloric acid : the tantalic acid 
separates as a white powder, which does not become yellow 
when heated. 



CLASSIFICATION OF MINERALS. 129 

Titanium in anatase, rutile, brookite, and titanite, is 
shown by the assay forming, with salt of phosphorus, in 
the oxidating flame, a glass which is and remains colorless ; 
in the reducing flame, a glass which appears yellow w^hen 
hot, and whilst cooling passes through red into a beautiful 
violet. When iron is present, however, the glass is blood- 
red, but is changed to violet by adding tin. When titanate 
of iron is dissolved in hydrochloric acid, and the solution 
boiled with a little tin, it acquires a violet color from the 
oxide of titanium. Heated with concentrated sulphuric 
acid, the titanate of iron produces a blue color. 



CHAPTER lY. 

CLASSIFICATION OP MINEEALS. 

A MINERAL species was formerly defined as a i;atural in- 
organic body, possessing a definite chemical composition 
and peculiar external form. The account given of these 
properties shows that the form of a mineral species compre- 
hends not only the primary or fundamental figure, but 
all those that may be derived from it by the laws of crys- 
tallography. Irregularities of form arising from accidental 
causes, or that absence of form which results from the 
limited space in which the mineral has been produced, do 
not destroy the identity of the species. Even amorphoiis 
masses, when the chemical composition remains unaltered, 
are properly classed under the same species, as the perfect 
crystal. 

The definite chemical composition of mineral species 
must be taken with equal latitude. Pure substances, such 
as they are described in works on chemistry, are very rare 

6'^ 



130 A POPULAR TREATISE ON GEMS. 

in the mineral kingdom. In the most transparent quartz 
crystals, traces of alumina and iron oxide can be detected ; 
the purest spinel contains a small amount of silica, and the 
most brilliant diamond, consumed by the solar rays, leaves 
some ash behind. Such non-essential mixtures must be 
neglected, or each individual crystal would form a distinct 
mineral species. The isomorphous elements introduce a 
wider range of varieties, and render the limitation of species 
more difficult. Carbonate of lime, for instance, becomes 
mixed with carbonate of magnesia or of iron in almost 
innumerable proportions ; and the latter substances also 
with the former. Where these mixtures are small in amount, 
variable in different specimens, and do not greatly affect 
the form or physical characters of the predominant element, 
they may safely be neglected, and the mineral reckoned to 
that species with which it most closely agrees. Where, 
however, the mixture is greater, and the two substances 
are frequently found in definite chemical proportions, these 
compounds must be considered as distinct species, espe- 
cially should they also show differences in form and other 
external characters. 

Amorphous minerals with definite composition must also 
be considered as true species. But when they show no 
definite composition, as in many substances classed as clays 
and ochres, they cannot be accounted true mineral species, 
and properly ought not to be included in a treatise on 
mineralogy. Some of them, however, from their import- 
ance in the arts, others from other circumstances, have re- 
ceived distinct names and a kind of prescriptive right to a 
place in mineralogical works, from which they can now 
scarcely be banished. Many of them are properly rocks, 
or indefinite combinations of two or more minerals ; others 
are the mere products of the decomposition of such bodies. 
Their number is of course indefinite, arid their introduction 



CLASSIFICATIOX OF MINFEALS. 131 

tends much to render mineralogy more complex and diffi- 
cult, and to destroy its scientific character. 

In collecting the species into higher groups, and arrang- 
ing them in a system, several methods have been pursued. 
Some, like Mohs, have looked only at the external charac- 
ters, and asserted that they alone were sufficient for all the 
purposes of arranging and classifying minerals. Others, 
led by Berzelius, have, on the contrary, taken chemistry as 
the foundation of mineralogy, and classed the species by 
their composition, without reference to form or physical 
characters. 

Neither system can be exclusively adopted, and a nat- 
ural classification of minerals should take into account all 
their characters, and that in proportion to their relative 
importance. Among these the chemical composition un- 
doubtedly holds a high rank, as being that on which the 
other properties will probably be ultimately found to de- 
pend. Next in order is their crystalline form, especially 
as exhibited in cleavage ; and then their other characters 
of gravity, hardness, and tenacity. But the properties of 
minerals are as yet far from showing that subordination 
and co-relation which has been observed in the organic 
world, where the external forms and structures have a direct 
reference to. the functions of the living being. Hence, even 
when all the characters are taken into account, there is not 
that facility in classifying the mineral that is presented by 
the other kingdoms of nature. Many, or rather most, of 
the species stand so isolated that it is scarcely possible to 
find any general principle on which to collect them into 
large groups, especially such groups as, like the natural 
families of plants and animals, present important features 
of general resemblance, and admit of being described by 
common characteristics. Certain groups of species are 
indeed united by such evident characters, that they are 



132 A POPULAR TKEATISE ON GEMS. 

found together in almost every method ; but other species 
are not thus united, and the general order of arrangement 
is very uncertain. Hence, though some classifications of 
very considerable merit have been proposed, no natural 
system of minerals commanding general assent has yet 
appeared. 

The arrangement followed in this treatise is chiefly 
founded on that proposed by Professor Weiss of Berlin. 
We have, however, made considerable changes, which the 
progress of the science and the more accurate knowledge 
of many species require. This classification appears to us 
to come nearer than any other we have seen to a natural 
system, which in arranging and combining objects takes 
account of all their characters, and assigns them their place, 
from a due consideration of their whole nature, and is thus 
distinguished from artificial systems, w^hich classify objects 
with reference only to one character. 

Besides species, two higher grades in classification seem 
suflScient at once to exhibit the natural relations, and to 
facilitate an easy and complete review of the species com- 
posing the mineral kingdom. These are families and orders. 
In forming the families, those minerals are first selected 
which occupy the more important place in the composition 
of rocks, and consequently in the crust of the globe. Thus 
quartz, felspar, mica, hornblende, garnet, among siliceous 
minerals; calc-spar, gypsum, rock salt, less so fluor spar 
and heavy spar, among those of saline composition, stand 
out prominently as the natural centres or rej^resentatives of 
so many distinct families. To these certain metallic miner- 
als, as iron pyrites, lead-glance or galena, blende, magnetic 
iron ore, the sparry iron ore, and a few more, are readily 
associated as important families. But the minerals thus 
geologically distinguished are not sufiicient to divide the 
whole mineral kingdom into convenient sections, and addi- 



CLASSIFICATION OF MINERALS. 133 

tional groups must be selected from the peculiarity of their 
natural-historical or chemical properties. Thus the zeo- 
lites are easily seen to form such a natural group. The 
precious stones or gems also, notwithstanding their diverse 
chemical composition, must ever appear a highly natural 
family, when regarded as individual objects. Their great 
hardness, tenacity, high specific gravity without the me- 
tallic aspect, their brilliant lustre, transparent purity, and 
vivid colors, — all mark them out as a peculiar group. Only 
the diamond, which might naturally seem to take the chief 
place in this class, differs so much, not only in elementary 
composition, but in physical properties, that it must be 
assigned to a different place. 

Round these species thus selected, the other less import- 
ant minerals are arranged in groups or families. It is evi- 
dent that no precise definition of these families can be 
given, as the connection is one of resemblance in many 
points, not of identity in any single character. In other 
words, it is a classification rather according to types than 
from definitions, as every true natural classification must 
be. The same cause, however, leaves the extent of the 
families somewhat undefined, and also permits considerable 
license in the arrangement of species. But both circum- 
stances are rather of advantage in the present state of the 
science, as allowing more freedom in the grouping of spe- 
cies than could be obtained in a more rigid system of clas- 
sification. 

In collecting the families into orders, the guidance of 
chemistry is followed rather than of natural history, though 
the latter is also taken into consideration. Chemical names 
are assigned to the orders, but still regarded as names de- 
rived from the prevailing chemical characters, and 7iot as 
definitions. Hence it must not be considered an error 
should two or three mineral species be found in an order 



134 A POPULAR TREATISE ON GEMS. 

with whose name, viewed as a definition, they may not 
agree. 

Guided by these and similar considerations, minerals 
may be divided into the following orders and famihes : 

Order I. — The Oxidized Stones. 

Families.— 1. Quartz. 8. Serpentine. 

2. Felspar. 9. Hornblende. 

3. Scapolite. 10. Clays. 

4. Haloid stones. 11. Garnet. 

5. Leucite. 12. Cyanite. 

6. Zeolite. 13. Gems. 

7. Mica. 14. Metallic stones. 

Order II. — Saline Stones. 

Families.— 1. Cale spar. * 4. Gypsum. 

2. ¥luor spar, 5. Kock salt. 

3. Heavy spar. 

Order III. — Saline Ores. 

Families. — 1. Sparry iron ores. 8. Copper salts. 

2. Iron salts. 4. Lead salts. 

Order IV. — Oxidized Ores. 
Families.— I. Iron ores. 4. Red copper ores. 

2. Tinstone. 5. White antimony ores. 

3. Manganese ores. 

Order V. — Native Metals. 
Form only one family. 

Order VI. — Sulphuretted Metals. 

• Families.— 1. Iron pyrites. • 4. Gray copper ore. 

\ 2. Galena. 6. Blende. 

3. Gray antimony ore. 6. Euby-blende. 

Order VII. — The Inflammables. 

Families.— I. Sulphur. ' 4. Mineral resins. 

2. Diamond. 5. Combustible salts. 

3. Coal. 



PART II. 



THE GEMS. 



PEECIOFS STONES OR GEMS. 

Peecious stones or gems are such minerals as, either from 
their beauty or other vakiable properties, have become the 
subject of the arts or trade, and are used as ornaments, or 
employed by jewellers. In order to appreciate more fully 
such minerals as may possess superior virtue, it is our pres- 
ent object to consider them in reference to their scientific 
and practical value. 

DIVISION OF GEMS. 

Gems are generally classed as follows : 1st, real gems, or 
jewels ; and 2d, semi-gems, or also precious stones. The first 
comprise such minerals as combine, within a small space, 
either vivid or soft and agreeable colors, with a high de- 
gree of lustre, usually termed fire, as well as hardness ; 
the second possess these characters in a less degree, and 
occur often semi-transparent or translucent, and in larger 
formless masses. It is, however, impossible to draw a 
Gtrict line between them, as the conventional value put upon 
the one or the other also afiects their character ; for very 
often some, which are generally considered as belonging 
to the second class, may be valued, for their peculiar prop- 
erties, much higher than some of the first class. 



136 A POPULAR TREATISE ON GEMS. 

Those species of minerals which are generally considered 
real gems are — 

Diamond, Garnet, 

Sapphire, TourmaUne, 

Chrysoberyl, Rubellite, 

Spinelle, Essonite, 

Emerald, Cordierite, 

Beryl, lolite. 

Topaz, Quartz, 

Zircon, Chrysolite. 

The rest are considered as semi-precious stones. 

COLOR, GRAVITY, AND HARDNESS OF GEMS. 

The precious stones possess the colors in their highest 
perfection, and their prmcipal and intrinsic value depends 
mostly upon this property ; and as most gems occur in va- 
rious colors, the following table will exhibit them, along 
with their specific gravity and hardness : 

LEVrPID GEMS. 

BPECIFIO GRAVITT. HARDNESS. 

Zircon. 4-41 to 4-70 7-5 

Sapphire 3-9 4-20 7' 

Diamond 3*5 3-6 10- 

Topaz (Pebble) 3-49 8-56 8- 

.Eock Crystal (False Diamonds, Lake George, 

Trenton Falls) 2-69 7* 

Beryl, Aquamarine 2-67 2-68 7*5 

BED GEMS. 

Zircon, Hyacinth 4-41 4-70 7*5 , 

Garnet (Oriental Garnet) 4-0 4-2 6-5 

Sapphire, Kuby 4*0 4*2 9- 

Garnet, Bohemian Garnet. Pyrop 8"7 8"8 6*5 

Spinelle, Euby Spinelle, Kuby Balais 3*49 3*7 8' 

Diamond 35 3-6 10' 

Essonite 3*5 3*6 7- 

Topaz. , Brazilian Topaz (often burnt) 8'52 3'56 8* 



GRAVITY AND HARDNESS OF GEMS. 137 

SPECIFIC GRAVITY. HARDNESS. 

Tourmaline, Siberite, Eubellite 8-0 to 3-30 6-5 

Eose Quartz, Bohemian Euby 2-50 2'63 7* 

Carnelian 2-5 2-6 7' 

YELLOW GEMS. 

Zircon 4-41 4*50 7-5 

Sapphire. Oriental Topaz 4*0 8' 

Chrysoberyl 3*65 

Topaz. Brazilian, Saxonian, and Syrian Topaz 3"50 

Diamond 3*5 

Beryl T.^.~. . . . 2-67 

Eock Crystal, Citron 2-60 

Fire-opal 1-90 

GKEEN GEMS. 

Zircon 4-41 

Sapphire, Oriental Chrysolite, and Emerald . . 3'9 

Malachite 3-67 

Chrysoberyl 3-59 

Spinelle 8-58 

Diamond 3*5 

Topaz. Aquamarine 3*49 

Chrysolite , 3*33 

Idocrase 3*08 

Tourmaline (Brazilian and Maine) 3*00 

Emerald 2*67 

Beryl 2*67 

Prase 2*66 

Heliotrope 2*61 

Chrysoprase , 2*58 

Felspar, Amazon Stone : 2*50 

BLUE (JEMS. 

Sapphire 3*90 

Disthene (Kyanite) 3*50 

Spinelle : . . 3*58 

Diamond 3*5 

Topaz. Brazilian Topaz 3*49 

Tourmaline, Indigolite 3*00 

Turquoise 2-86 

Beryl, Aquamarine 2*67 

Dichroite (lolite) 2*58 



8*80 


.8*5 


8*56 


8* 


3*6 


10- 


2*71 


7*5 


2*69 


7- 


2*12 


5*5 


4*50 




4-00 


8- 




8*5 


8-75 


8*5 


3-64 


8* 


3*6 


10- 


3*56 


8* 


3*44 


6*5 


3*40 


6*5 


3*30 


6*5 


2*73 


7*5 


2-71 


7*5 


2*68 


7* 


2*63 


7* 


2*60 


7* 


2-60 


6- 


4*00 


8* 


5*67 


5- 


8*64 


8* 


3*6 


10* 


3*56 


8* 


3-30 


6*5 


3*00 


6* 


2-71 


7*5 


2*60 


7- 



138 A POPULAR TREATISE ON GEMS. 

SPECIFIC 6RAVITT. HAKCNESS 

Hauyne 2-47 . 5- 

Lazulite 2-30 5- 

VIOLET GEMS. 

Garnet 4-0 to 4-2 6*5 

Sapphire, Oriental Amethyst 3*9 4*0 9* 

Spinelle 3-58 3-64 8* 

Axinite 3*27 6;5 

Tourmaline 3*00 3-30 6-5 

Amethyst 2-65 2'7S 7" 

BROWN GEMS. 

Zircon 4-41 4-50 7-5 

Garnet 4*00 4-20 6'5 

Essonite 3-53 3-60 7" 

Diamond 3*50 3-60 10* 

Tourmaline 3-00 3-30 6*5 

SmokyQuartz 2*69 2-70 7* 

BLACK GEMS. 

Diamond 3'50 3-60 10* 

Tourmaline 3:00 3*30 6- 

Rock Crystal, Morion 269 2-71 7* 

Obsidian .' 2-34 2-39 6-5 

Pitch Coal 1-29 1-35 2- 

CannelCoal 1-23 1*27 2- 

GEMS DISTINGUISHED FOB THEEB VARIOUS SHADINGS OF COLOR 
AND LIGHT. 

Garnet 4-00 4'20 6-5 

Sapphire, Star Sapphire .• 3*90 4*00 9* 

Chrysoberyl 3-70 3-80 8-5 

Hypersthene 3'38 6- 

Labrador Spar '... 2-71 2-75 6- 

Dichroite ; 2-58 2-60 7- 

CatVeye 2-56 2-73 7' 

Adularia 2-50 2-60 6- 

Felspar 2-50 2-60 6' 

Precious Opal 2-00 2-10 5-5 

Hydrophane 1-90 2-00 5- 

A number of precious stones do not possess a local color, 



COMPOSITION OF GEMS. 139 

but merely a tinge or a shade of color ; and these we dis- 
tinguish by the following degrees of dark,* high, light, and 
pale colored, or tinged. Another distinction may be de- 
tected in precious stones as possessing either one or more 
colors, or a variegated color ; or as being spotted, painted, 
stained with the different colors. These latter characters 
are, however, more proper to the semi or common precious 
stones, than to gems. 

CHEMICAL CHARACTERS. 

Although mineralogy could not exist, as a science, with- 
out the aid of chemistry, and whole systems or classifica- 
tions have been established, as well as the constituent parts 
of minerals determined, by the knowledge of chemical char* 
acters, still it is difficult to resort to chemical means for dis- 
tinguishing the gems or j^recious stones, as they would be 
destroyed by such an examination, and we can, for that 
purpose, only employ splinters or fragments. The most 
simple mode of proceeding is to test — 

1st, Their greater or less fusibility, with or without a flux ; 

2d, Their behavior before the blowpipe, an instrument 
highly convenient, and, indeed, indispensable to the miner- 
alogist ; and, 

3d, The action of the acids upon them. 

All of these means, however, have not an effect upon all 
gems, as many of them, for instance, are either infusible, or 
fusible with the greatest difficulty by the addition of a flux. 

COMPOSITION OF GEMS. 

The attention of writers, as far back as 1502, had been 
directed to the establishment of some hypothesis as to the 
composition and origin of the gems, and. many fabulous 
views were entertained in respect to their formation. 

There was also connected with some hypotheses a species 



140 A POPULAE TREATISE ON GEMS. 

of medical superstition as to their effect. Boyle (16 7 2) 
thought that all gems were originally formed from clear 
limpid water, and that they received their color and other 
properties from their metallic spirit. Others considered a 
peculiar earth, called the noble or precious earth, as the 
principal ingredient of the precious stones. Bruckman 
(1778) recognized quartz as the principal of the gems. 
Bergman thought that gems were all composed of the same 
ingredients, such as alumina, silex, and lime, and that the 
different proportions produced the different species ; and 
the older mineralogists determined the character of the 
gems by their hardness, lustre, structure, and resistance to 
acids. But modern chemistry has ascertained the compo- 
nent parts, and other characters of gems, with more cer- 
tainty, and it is satisfactorily proved that the principles 
they contain are the earths, such as silica, alumina, and 
lime ; that some contain a peculiar earth (such is the case 
with the zircon, emerald, and chrysoberyl), and that the 
diamond, at the head of gems, consists of pure carbon, &c. 

THE ARTIFICIAL PRODUCTION OF GEMS AND MINERALS. 

Professor Mitscherlich has produced, artificially, crystals 
of minerals by fusion at a high temperature of the scoria 
of furnaces containing silicates, with the addition of such 
oxides as form a component part of the respective minerals, 
exposed to a high heat. So successful was the result, that he 
produced more than forty species of the various crystalline 
minerals artificially, and corresponding Avith the natural 
productions, such as peridote, pyroxene, mica, felspar, pro- 
toxide of copper, iron pyrites, and others. Beithier devoted 
likewise some time in reproducing several minerals by fusion 
at a high temperature, and he has obtained crystals of peri- 
dote and pyroxene with iron and manganese bases, which 
were for a long time called silicate of manganese. 



ARTIFICIAL PRODUCTION OF GEMS. 141 

Mr. Gaudin has, by means of the compound blowpipe, 
been able to fuse alumina and quartz, and from potassa 
and ammoniacal alum he has produced well-formed co- 
rundum crystals, as also crystals of ruby, of rhombohe- 
dral form and triple cleavage, and which, according to 
Malagutti, consisted of ninety-seven alumine and two silicate 
of lime, the exact composition of ruby. By this process 
the potassa originally employed was volatilized in the high 
temperature; this was done in 1837. Becquerel employed 
electricity for this purpose in its most attenuated condition, 
and with two or three bodies, one of which in its dry and 
the other in liquid state, and required from one to two 
years to effect its object, as the case was with a dodecahe- 
dral pentagonal crystal of iron pyrites; he obtained sulphu- 
rets of copper and tin, which could not be distinguished 
from the native crystals. He has even obtained crystals of 
oxide of zinc, which were octahedral, transparent, refract- 
ing strongly the light, and hard enough to scratch glass, 
and altogether unknown in the mineral kingdom. His 
process was, on a silicate of potassa solution to let act 
slowly a voltaic current from a sheet of zinc, around which 
a copper wire was wound. The density of the liquid was 
22° areometer; water was thereby decomposed with dis- 
engagement of hydrogen gas and formation of oxide of 
zinc, which was dissolved again, and after a fortnight, very 
fine brilliant crystals were visible on the zinc plate, which, 
after a lapse of two years, were the size of a millimeter. 

Mr. Ebelman conceived the idea of obtaining artificial 
crystals from infusible silicates and aluminates, by replac- 
ing the water contained in many metallic oxides in high 
temperatures with boracic acid, borate of soda, phosphorus, 
and alkaline phosphates, and its final evaporation in high 
temperatures. He prepared certain ojddes, calculating 
the proportions, such as alumina and silica, and exposed 



142 A POPULAR TEEATISE OX GEMS. 

them in a platina capsule, atr a high temperature, in his 
porcelain furnace of the S5vres manufactory, of which he 
was the director, and with the mixture of boracic acid kept 
the mass in a fusion, and the corundum and crystallized 
silex were the results. He used boracic acid for this purpose, 
as he found it more convenient than the. other dissolvents. 

Mr. Ebelman has fused together, in order to obtain the 
spinelle (which is composed of 72 parts of alumina and 28 
parts magnesia). 

Alumina, - - - 6 grammes. 

Magnesia, - - - 3 " 

Fused boracic acid, - 6 " 

Green oxide of chrome, 0*10 to 0" 15 grammes. 
The latter was added for the purpose of rendering the mass 
of a rose color. This mixture, put into an uncovered pla- 
tina capsule, was exposed to the heat of the porcelain fur- • 
nace ; after the baking was finished, the melted mass formed 
a rose-colored layer on the bottom of the capsule, and in 
the mass octahedral crystals of spinelle, quite identical with 
the natural crystals of the ruby spinelle, were taken out, 
which were exceedingly brilliant. The author received in 
1851, while on a visit to Paris, from Mr. Ebelman, about 
thirty of those crystals, weighing about one grain, and 
which he submitted, on his return to the United States, to 
numerous chemical and mineralogical tests, both as to 
hardness, specific gravity, and lustre, and was extremely 
gratified as to its results. 

Mr. Ebelman manufactured the blue spinelle, by substi- 
tuting the same quantity of oxide of cobalt for the oxide of 
chrome ; also by substituting the oxide of zinc for the 
magnesia, he obtained the garnet, which he prepared by 
Alumina, - . - 6 grammes. 
Oxide of zinc, - 5 " 
Fused boracic acid, 6 " 



ARTIFICIAL PRODUCTION OF GEMS. 143 

The mass yvsls brought slowly to a white-heat temperature, 
and kept from twenty-four to thirty hours in that condition. 
The boracic acid begins to evaporate during the last five 
hours. 

The emerald was obtained artificially by a mixture of 

Silex, - - - 4 grammes. 

Alumina, - - 1*60 " 

Glucia, - - - 1-40 " 

Fused boracic acid, 4*06 " 

Oxide chrome, - 0*10 " 
Mr. Daubree has produced artificially the oxide of tin, 
by passing through a heated porcelain tube two currents 
of the vapors of the perchloride of tin and water, by which 
a double decomposition was eifected, so that in the interior 
of the porcelain tube small crystals of oxide of tin were de- 
posited, and hydrochloric acid gas passed off in the form of 
vapor. The crystals of tin were deposited at the orifice of 
the porcelain tube, where the temperature was scarcely 
300°, while no crystals were deposited in the hottest part ; 
the crystals of tin scratched glass easily, were infusible, 
and were not affected by acids, and had a specific gravity 
of 6-72. 

The latest discoveries of Mr. Daubree have brought to 
light many important facts in regard to the formation of 
rocks which contain crystalline substances, differing widely 
in their fusibility. By the action of chloride of silicium at 
red heat, and vapor on many bases which enter into various 
rocks he obtains in exchange, by decomposition, chlorine 
bases and free silica (silicic acid), which appears as quartz 
in crystals ; if he desires an action of the chloride of sili- 
cium on chalk, magnesia, alumina, or glucia, he obtains 
crystals of quartz, wallastonite, peridote, and disthene ; for 
the purpose of obtaining double silicates, he not only adds 
the bases for silicifying in proper j^roportions, but also in 



144 A POPULAR TREATISE ON GEMS. 

excess sufficient oxygen for forming silicic acid. A mixture 
of chalk or magnesia, for instance, to the chloride of sili- 
cium, produced crystals of diopside, perfectly colorless, 
with a characteristic slope of this mineral. He also ob- 
tained crystallized felspar by the mixture of 1 equivalent 
of alkali (potassa and soda), 1 equivalent of alumina, with 
6 equivalents of lime under the influence of chloride of si- 
licium. Similar mixtures have produced crystals of garnet, 
idocrase, phenakite, emerald, euclase, zircon, and wilhelm- 
ite. He also produced tourmaline in regular hexagonal 
prisms, which were grouped upon quartz crystals just as 
they are often observed in crystalline rocks of shorl. By 
the same method, but replacing the chloride of aluminum 
for action upon the bases, he obtained corundum crystals, 
spinelle crystals, and garnet crystals; by the contact of 
perchloride of iron with chloride of zinc he obtained fine 
crystals of franklinite; crystals of magnesia or periclase, 
like those from Mount Somma, were produced by the 
action of lime on chloride of magnesium, but remarkable 
enough, their production is just the counterpart of the ori- 
gin of the native mineral, where constantly chlorine vapors 
are disengaged, and where it detaches itself from the dolo- 
mite geodes. 

Mr. Durocher obtained, by the action of sulphuretted 
hydrogen gas upon the chlorides of iron and zinc, crystals 
of magnetic pyrites and blende ; he also obtained, by the 
action of different vapors, sulphurets of antimony and 
arsenic, and the gray antimonial copper. 

Mr. Senarmont obtains quartz crystals in perfect hexag- 
onal prisms, with all the other specific characters, from the 
gelatinized silica, under a high temperature and the high 
pressure of thirty atmospheres. 

The artificial production of the diamond has been latterly 
effected by the ingenious contrivance of Despretz, w^hich 



I 



GEOLOGICAL CHAEACTEES. 145 

consists in passing an electric current into an exhausted 
bottle, in the lower part of which is placed a small cylinder 
of charcoal, and from the upper part are suspended pla- 
tina wires or platiua foils; the sparks thereby obtained 
from the combustion of the charcoal are of a reddish-violet 
color; after the lapse of one month, during which the com- 
bustion continues, a little black layer of charcoal is depos- 
ited upon the platina ; under the microscope they appear 
like very small octahedrons, quite analogous to the dia- 
mond ; some were free from color, and very brilliant. 

GEOLOGICAL CHAEACTEES. 

The origin, locahty, and geological characters of gems 
are various ; it was formerly supposed that the trap forma- 
tion was their matrix ; but it is ascertained that we find 
them distributed in rocks of different ages and kinds, either 
as accidental mixtures — such as garnet in gneiss and mica- 
ceous schistC' — or in drusy cavities, such as the emerald, 
which occurs in druses of argillaceous slate and micaceous 
schiste ; and many precious stones are found in gangues. 
Many gems are found at a distance from their original bed, 
on secondary or diluvial strata, or in the beds of rivers, 
mixed with their sand. Thus, zircon is found in Ceylon in 
regular beds ; and likewise we find in Ceylon, after much 
rain, the topaz, zircon, and other gems. This hapjDens 
more frequently in the beds of the rivers, and then ^the 
gems appear often in the shape of pebbles, showing that 
those hard stones, carried away from their original beds, 
have been rolled and rounded by the streams and rivers, 
although they retain sometimes their crystalline structure, 
on account of their hardness. 

The discove]'y of diamonds in Russia, far from the tropi- 
cal region, has excited much interest among geologists. 



146 A POPULAR TPvEATISE ON GEMS. 

In the detritus on the hanks of the Adolfskoi, no fewer 
than forty diamonds have been found in the gold alluvium, 
only twenty feet above the stratum in which the remains 
of mammoths and rhinoceroses are found. Hence Hum- 
boldt has concluded that the formation of gold-veins, and 
consequently of diamonds, is comparatively of recent date, 
and scarcely anterior to the destruction of the mammoths. 
Sir Roderick Murchison and M. Yerneuil have been led to 
the same result by different arguments. 

GEOGRAPHICAL DISTRIBUTION. 

The locality of gems bears some highly, interesting 
characters, inasmuch as w^e may sometimes judge, from 
their appearance, the climate of their locality ; and it 
seems as if the countries of the torrid zone had been par- 
ticularly favored by nature in producing the most precious 
gems, or that those hot-beds were more propitious to the 
formation of the blossoms of the inorganic world. Com- 
paring, for instance, spinelles and zircons, from Siberia,' 
with those of Ceylon and Peru, w^e find the first to be dark 
and of an impure color, as if emblematic of a cold, un- 
friendly, northern climate ; whereas the latter glitter with 
full brilliancy, and possess all those properties and beauties 
for which gems are so highly esteemed. Often, too, we 
find the gems collected in particular countries, or isolated 
spots of our globe, such as the most precious gems from 
the East Indies and Brazil, where, singular -enough, they 
occur with the precious * metals ; as, for instance, the dia- 
mond in company with gold and platina in Brazil. Some 
of the gems have likewise been hitherto discovered in a 
single spot on one continent only, and are then exhausted ; 
such as the rubellite, in Maine, United States ; the iolite in 
Connecticut, United States, and the lazulite in Persia. 



NOMENCLATURE OF GEMS. 147 



PRACTICAL DIVISION AND NOMENCLATURE OF GEMS. 

Artists have not profited, in their arrangement and no- 
menclature of gems, by the advanced state of mineralogy, 

' as a science ; and although they have been newly classified 
by mineralogists according to their scientific characters, 
the practical artist arranges them according to those prop- 
erties that principally attract the eye : such as color, trans- 
parency, and lustre. Gems have, in consequence, received 
their names from their color : as ruby, from, its red color ; 
sardonyx, yellow onyx. Gems of different species, but of 
the same color, are often named from their color. For 
instance, the corundum, the sj)inelle, or the topaz, if of a red 
color, is called ruby ; if blue, sapphire ; if green, emerald ; 
if yellow, topaz, and if violet, amethyst : and thus gems of 
the same color, but of different composition, are arranged 
under the same head. The artist confounds under the 
name of Brazilian ruby, either a light rose-red spinelle, 
or a topaz approaching to the red color. The name of a 
country or locality, is often sufficient to give a name to gems 
of the same color, but of different shadings, and of more 
or less vivid lustre. Thus, by Oriental chrysolite is meant 
a yellowish-green sapphire, and by Saxonian chrysolite, a 
pale wine-yellow topaz. Many gems have always been 
known under the name of Oriental gems, partly because 
they were first obtained in the East, and partly because 
they stood, from their excellent properties, iri higher esti- 
mation than those from any other country. Those from 
the East w^ere likewise called " Oriental," in opposition to 
others less valuable, which were called " occidental" gems. 

] Subsequently, all gems of superior qualities were called 
Oriental gems, even when their locality was not in the 
East. Thus, for instance, that precious opal, so well dis- 
tinguished for its beautiful play of colors, is called the Ori- 



148 A POPULAR TREATISE ON GEMS. 

ental opal, although it is never found there ; likewise, the 
purest and most valuable emerald, which in great perfection 
only occurs in Peru, is known as the Oriental emerald. 

HISTORY OF GEMS. 

Those precious stones, which are now called gems, were 
known in ancient times but very little, if at all. The first 
notice given of them is in the Bible, where it is stated that 
the high priest wore one stone on his gold scarf, and twelve 
gems set in gold plate, called the Urim and Thummim, 
each of which represented a tribe. It appears that the 
Hebrews bctrrowed the names of their gems from the 
Egyptians, and few of the gems — with the excej^tion of 
the sapphire — named in the holy Scriptures correspond in 
any respect with those at present known in our mineralogical* 
books. The Greeks appear to have been but little ac- 
quainted with gems, as they did not use them as ornaments 
in the Trojan w^ars; and Homer, when speaking of the 
treasures of those times, does not make any mention of 
gems. Theophrastus and Pliny have described some gems 
of their time very imperfectly and confusedly ; and their 
descriptions are so replete with vain fancies, that it is diffi- 
cult to identify any from their descriptions. They attributed 
most wonderful pow^ers to gems ; gave fabulous descriptions, 
and the most singular and perverted views in regard to 
their origin ; and it w^as said that they had great influence 
upon health and beauty, riches, honor, and good fortune. 
They were called, when worn, amulets. They were brought 
into connection with the planets, the twelve constellations, 
and the seasons of the year ; and a certain gem was worn'^ 
each month, which was said to have during the term, its pe- 
culiar influence and healing virtues. Such superstitious 
notions have been transmitted to our times. The gems cor- 



J 



HISTOEY OF GEMS. 149 

responding to the different months, and also to the twelve 
Jemsh tribes, are the following : 

January Hyacinth Dan. 

February Amethyst Gad. 

March Jasper Benjamin. 

April Sapphire Issachar. 

May Agate Naphtali. 

June Emerald Levi. 

July Onyx Zebulon. 

August Carnelian . ,^ Reuben. 

September Chrysolite Asher. 

• ■ October Beryl . .•• Joseph. 

November Topaz.., Simeon. 

December Ruby - Judah. 

• 
Artists have made certain changes in some of the gems 

corresponding to the months, and the tribes represented 
in the Urim and Thnmmim"; they consider May to be repre- 
sented by emerald : 

June ' by Chalcedony, Onyx, or Agate ; 

July Carnelian ; 

August. . . . .* Sardonyx ; 

October Aquamarine ; 

December Chrysoprase, Turquoise, or Malachite. 

In the early ages similar views were entertained in the 
East, and many of them are yet prevalent. The Persians 
believe that spinelle affords joy, and protects them against 
bad dseams. The Indians believe in the efficacy of large 
diamonds to bring them back to their families. (The Rajah 
of Mattan, a district of Western Borneo, possessed a dia- 
mond of 367 carats.) The ruby is esteemed, in the East, 
as a talisman, which is never sho^ni willingly to friends ; 
it is considered ominous if it contains any black spots. The 
Chinese, on the contrary, present the same stone as a testi- 
mony of friendship. The Peruvians adore the emerald as 



150 A POPULAR TREATISE OX GEMS. 

their deity. Many of these fabulous notions were probably 
brought from the East to Europe; for we find, in the 
middle ages, similar views entertained by Marbodus, Bishop 
of Rennes, who wrote a book on the miraculous powers of 
gems. The twelve Apostles were likewise I'epresented 
symbolically by gems, and they were called " tlie Apostle 
gems;" as — 

Jasper ^ for St. Peter ; 

Sapphire • St. Andrew; 

Chalcedony St. James ; 

Emerald St. John ; • 

Sardonyx St. Philip ; 

Carnelian St. Bartholomew ; 

Chrysolite St. Matthew ; 

Beryl St. Thomas ; 

Chrysoprase St. Thaddeus ; 

Topaz St. James the Less ; 

Hyacinth St. Simeon ; 

Amethyst St. Matthias. 

The ancients, induced by the beauty of gems — the pure 
and deep colw of the emerald, the vivid and high lustre 
of the diamond, and the agreeable reflections of the opal 
— had commenced using them as ornaments and jewelry, 
and they took pains to adapt them to their purposes. 
Although they did not, in those times, understand the art 
of cutting and polishing them as practised at the present 
time, yet they endeavored to work them into all possible 
shapes, by rubbing off the coraers, or polishing the natural 
faces. They generally fixed the gems on strings ; they 
also tried to carve figures representing deities, religious 
costumes, historical events, exploits of celebrated generals, 
or the heads of great men. 



SCULPTURE IN GEMS. 151 



SCULPTURE IN GEMS. 



The art of carving was well known to the ancients, and 
those stones were called gems, in the proper sense of the 
word, which had figures or letters engraved on them in a 
very small compass, the workmanship of which we, at this 
day, cannot help admiring. 

Gem-sculpture, or the glyptic art (or lithoglyptics), is the 
art of representing designs upon precious stones, either in 
raised work (cameos) or by figures cut into or below the 
surface (intaglios). The first were most natural to the 
rising art, and were used as seals ; whereas the latter were 
used as ornaments, for which the most precious materials 
were employed, according to the state of the art. They 
did not understand engraving on diamonds, or many 
other gems : they employed only the softer stones, the 
common precious stones, such as carnelian, onyx, jasper, 
&G. ; they also used paste, or artificial colored glass compo- 
sition, for their engravings. Their mode of working was 
very simple : the polishers prepared their stones on a plate, 
by means of the powder of harder stones, either round, 
oval, flat, or in shield form, according to the designed sub- 
ject, and then left to the sculptors the subject of the en- 
graving, which was done by means of iron, or diamond 
splinters mounted in iron. It was not until the year 1500 
that Ambrosius Caradossa first discovered the method of 
cutj^ing the diamond. He prepared the figure of a patriarch 
for Pope Julian II. He also discovered the first traces of 
sculpture among the Jews, Persians, and Egyptians. In 
the traditions of the holy Scriptures, Moses, for instance, 
had the names of the twelve tribes of Israel engraved on 
the gems used by the high-priest. Solomon possessed a 
seal : Alexander presented his seal to Perdicas. Augustus 
had a sphinx engraved on his seal; but the' Indians and 



152 A POPULAR TREATISE ON GEMS. 

Persians engraved mostly mythological animals or priests 
in their gems ; the Egyptians, beetles, which they adored, 
and which are called the scarabs^. " Abraxes" were the 
oldest gems, which had the representation of fantastical 
animals, with the above word in the Greek language, en- 
graved on them. 

The Phenicians, Hetrurians, aod Greeks learned the 
art of carving from the Egyptians ; and from them it was 
carried to the Romans, where it was lost, in the decline 
of the emjiire, in the fifteenth century, under the PojDes 
Martin Y. and Paul II. The art was revived again by 
some fugitive Greeks in Italy. Great merit is also due to 
the Medicians for the revival of the art ; and Giovani was 
considered the first in Italy. The talisman^ or carved 
gems bearing Arabian letters, belong to those times. 
Precious stones with layers and veins, or such as onyx, sar- 
donyx, &c., were employed by the ancients, with great 
skill, in the carving of cameos, where Ave find the head of 
one color, and the hair and dress of a different color carved 
out of the other layer of the stone. Very often the sub- 
jects were mythological, and this mode of carving or sculp- 
ture has been imitated by modern artists. It is sometimes 
with difficulty that we are enabled to distinguish the an- 
cient from the modern works, and the only authentic 
authority for the antiquity of the cameo or intaglio is its 
excavation from ancient monuments, except in a few in- 
stances, where we may be able to jndge by comparison of 
the difference in antiquity ; by observing whether or not 
they are unnaturally, or stiffly done; have large heads, 
hands, and feet, or stiff" streaks resembling the hair, &c. 
We find that some gods, representing the peculiar gems 
(such we see all sculptures of Bacchus, and what relates to 
him), were executed in amethyst, being the color of wine ; 
and all nymphs, Neptune, or fish, in aquamarine, &c., the 



ON GKINDING. 



153 



color of water. We find also, in Germany, traces of sculp- 
ture in the fourteenth and sixteenth centuries ; the oldest 
known artist, Daniel Engelhard, at ISTuremburgh, died in 
1552 ; also Lucas Kilian; and the best artist, ISTater, died 
in 1705. England and France had likewise very distin- 
guished artists in carving. A full history of gem-sculpture 
may be found in the Encyclopedia Americana, pp. 403-405. 



ON GRINDING. 

The art of grinding gems is of more modern origin ; it 
consists in cutting the gems, and other precious stones, into 
figures, bounded by many planes, and by polishing the 
faces thus formed, increasing their lustre, transparency, and 
other valuable properties. This constitutes the work of 
the lapidary. In the year 1290 a society of lapidaries was 
formed at Paris, and in 1385 there were diamond-cutters at 
ISTuremburgh ; but it w^as not until 1456 that Ludwig Yan 
Bergen invented the art of polishing the diamond Avith its 
own powder; gems were then cut according to mathe- 
matical principles; the art has been brought, in modern 
times, to the greatest perfection. There is a great difference 
in gems (which are mostly procured from the Indies in a 
rough or polished state), easily to be detected by their im- 





Fig. 1 a. 



154 



A POPULAR TREATISE ON GEMS. 



perfections. The Indians look more upon the size of the stone 
than upon the cut, which is generally irregular and devoid 
of symmetry. We observe this in the two celebrated dia- 
monds of the Shah of Persia, the Dariainur — brilliant sea 
— (figs. 1 and 1 a), and the Kuinur — hrilliant mountain — 
(figs. 2 and 2 a) : the one is worn on the left arm, and the 
other on the right knee. 




r.irx-tf>v.».««n>u>uj.n. 



Fig. 2. 



^^^^j:<^^^iv^j^2^^W^Wic<^\ 






^ 



■ATATA'ff.-y^t.T.-t.T.yATA-yTX'H?-^ 



El 



FiR. 2 a. 



By looking at the subjoined representation of the dia- 
mond belonging to the crown of France (figs. 3 and 3 a\ 
^vhich weighs one hundred and thirty-six and a quarter 
carats, is fourteen lines long, thirteen and a quarter lines 
broad, and nine and a quarter lines thick, and which is 
known by the name of Regent^ we can more distinctly dis- 
criminate the irregular and un mathematical cut. 

The gem-grinders are divided into three classes: first, 



ON GRINDING. 155 




Fig. S. Fig. 3 a. 

the diamond ; second, the gem ; and third, the jewelry- 
grinders. 

The diamond grinder divides his work into — a, slitting 
or cleaving ; 5, cutting ; c, grinding ; and d, polishmg. 

Before operating upon diamonds, some preliminary ex- 
periments as to their soundness are made: for very fine 
imperceptible fissures may, at the end of a laborious grind- 
ing, terminate either in cracking or spoiling the stone. 
An examination for this purpose is made in one of the two 
following modes : either the diamonds, or any other gems 
to be examined, are steeped in Canada balsam, or in oil of 
sassafras or aniseed, in w^hich fluid they are well turned 
around, whereby the minutest fissure, on account of its 
changed refraction of light from that of the rest of the 
stone, may be detected ; or the diamond is exposed to a 
great heat, and is then thrown into water, when it will 
crumble to pieces should any cracks exist within it. The 
diamond, although the hardest of all known substances, 
may yet, with facility, be cloven with steel tools, the blow 
being properly applied. The octahedrons are best fitted 
for cleaving : they are generally, however, somewhat 
rounded, and in order to cleave them, those planes which 
are to be cloven, are left bare, and the rest is coated with 
a composition of resin and brick-dust ; the bare plane is 
now rubbed with another sharp-edged diamond until a 



156 A POPULAR TREATISE ON GEMS. 

V 

fiiiTOW is obtained, which Avill render the planes suitable 
for applying the cleaving instrument, and this operation is 
repeated with every plane. Diamonds that are not fit for 
being cloven, are called by the Dutch, " divelstee?ie'^ (devil- 
stones). Large diamonds, which are too precious to be 
expose to a dangerous- cleavage, are sawed by means of a 
fine steel wire, moistened with oil and diamond-powder. 

The rough-cut diamonds, as they are brought from the 
Indies, are called labora. 

Mr. Mawe gives the following description of the art of 
cutting and polishing diamonds : 

" The object of cutting and polishing the diamond is 
twofold : 

" First, to divide the natural surface of the stone in a 
symmetrical manner, by means of a number of highly- 
polished polygonal planes, and thus to bring out to the 
best advantage the wonderful refulgence of this beautiful 
gem ; and, secondly, by cutting out such flaws as may 
happen to be near the surface, to remove those blemishes 
that materially detract from its beauty, and consequently 
from its value. 

" The removal of flaws is a matter of great' importance: 
for, owig to the form in which the diamond is cut, and its 
high degree of refrangibility, the smallest fault is magnified, 
and becomes obtrusively visible in every facet. For this 
reason, also, it is by no means an easy matter, at all times, 
to ascertain whether a flaw is or is not superficial; and a 
person with a correct and well-practised eye may often pur- 
chase, to great advantage, stones which appear to be flawed 
quite through, but are, in fact, only superficially blemished. 

" The first thing the artist has to do, when a rough dia- 
mond is put into his hands, is to exaitiine carefully in what 
direction the stone may be cut, so as to afibrd the greatest 
breadth, or spread^ as it is technically termed, after the 



ON GRINDING. 157 

flaws, if any, shall have been taken out. So great a stress 
is laid, by modern fashion, on the superficial extent of a 
brilliant, that the old rules of proportioning its dimensions 
are now nearly obsolete : the best cutters have entirely 
discarded the use of measures, and, in forming the facets, 
trust wholly to an accurate and well-practised eye. The 
direction being determined on, the artist must be well 
aware which are the hard points and which the soft ones ; 
the former being those solid angles of the original octahe- 
dron, which it is necessary to cut directly across, and the 
latter those solid angles which are 4o be obliquely divided. 
A degree of force which may be safely apj)lied, and is even 
requisite in making a section through the former, will be 
very a|)t to flaw and tear up the lamina3 when applied to 
latter. On these accounts it probably is, that the fatiguing 
and even painful process of ^^erforming this part of the' 
business by hand, is not yet superseded by the use of 
machinery. 

" These preliminary matters being settled, the diamond 
is imbedded in a strong cement, fixed at the end of a stout 
spindle-shaped stick, about a foot long, with that portion 
only projecting, the removal of which is to form the first 
facet. The instrument employed for this purpose is another 
diamond, fixed in a stick similar to the former, wdth one of 
the solid angles projecting. In order to collect the powder 
and shivers that are detached during the process, the cut- 
ting is performed over a strong box, four or five inches 
square, furnished with a false bottom perforated with ex- 
cessively minute holes, in order to sift, as it were, the dust 
from the shivers; and also with two upright iron pegs, 
fixed on the sides, for the workman to support and steady 
his fingers against, while with a short repeated stroke,- 
somewhat between scratching and cutting, he is splitting 
off, or more laboriously w^earing away the diamond in that 



158 A POPULAR TREATISE ON GEMS. 

part where the facet is to be placed. This being done, the 
cement is softened by warming it, and the position of the 
diamond is changed, in order to bring a fresh part under 
the action of the cutting-diamond. When, in this slow 
laborious way, all the facets have been placed upon the sur- 
face of the diamond, the cutting is completed. The stone, 
if examined by a moderate magnifier, now presents ragged, 
rough edges ; and a broken, foliated surface, with a glisten- 
ing lustre on those facets that are nearly in the direction 
of the natural laminae, and on the other facets a more even 
surface, but of a dull opaque grayish-white color. 

" The shape of many diamonds is so irregular, that it is 
necessary to remove pieces of considerable magnitude in 
order to bring them to a form proper for cutting. Where 
the lines of these proposed sections coincide wdth the 
natural lamellar structure of the stone, the workman has 
recourse to the delicate, and perhaps somewhat hazardous, 
operation of splitting the diamond, by which a double ad- 
vantage is obtained. In the first place, there is a great 
saving of time ; and in the second place, the slices or shivers 
are themselves sufiiciently large to admit of being cut and 
polished. The method of splitting is made a great mystery ; 
thus much, however, may be mentioned, that when the 
direction in which the section is to be made has been deter- 
mined on, it is marked by a very fine line, cut by the 
point of another diamond : the stone is afterwards fixed 
by strong cement in the proper position, in a block of wood, 
and then, by the application of a due degree of force, the 
section is effected. 

" The diamond being thus, by the joint action of split- 
ting and cutting, brought to the required form, the next 
object is to polish the facets, and at the same time to 
redress any little inequalities that may have taken place in 
the catting. The polishing-mill is an extremely simple 



1 



ON GRiNDING. 169 

machine, consisting of a circular horizontal plate of cast- 
iron, fourteen or fifteen inches in diameter, called a shive^ 
suspended on a spindle, and capable of being put into rapid 
motion by means of a larger wheel, five or six feet in 
diameter, and turned by an assistant. From the centre to 
the circumference of the iron plate, are lines or shallow 
grooves, formed by rubbing it in that direction with a fine 
grained gritstone : these grooves serve to retain the mix- 
ture of oil and diamond-powder with which the plate is 
charged. In order to keep the diamond perfectly steady 
while the polishing of e!tch facet is going on, the following 
contrivandfe is had recourse to : — a copper cup, called a dopp^ 
about three quarters of an inch in depth and in width, and 
furnished with a stem about four inches long of stout 
copper wire, is filled with plumbers' solder, which also pro- 
jects in a conical form beyond the rim of the cup : in the 
apex of this cone, the solder being softened by heat, the 
diamond is imbedded with one of the facets projecting. 
The stem of the cup is now put into very powerful pincers, 
which screw up with a nut and a wrench or lever, and thus 
hold it perfectly tight. The handles of the pincers (made 
of wood, and called tongs) are broad, and terminate in two 
feet, about an inch high, so that when laid horizontally, 
they are supported exactly as a pair of candle snuffers are, 
the studs fixed to the handles of the snuffers representing 
ing the legs of the pincers, and the single stud near the 
point of the snuifers representing the inverted copper cup 
•holding^the diamond is placed on the plate, the pincers rest- 
ing on their legs on the wooden bench or table that sup- 
ports the plate, and pressing at the same time against an 
upright iron peg ; the broad part of the pincers between 
the legs and the diamond, is then loaded with weights, 
both to steady the machine, and to increase the pressure of 
the diamond against the skive. Matters being thus ad- 



160 A POPULAR TREATISE ON GEMS. 

justed, a, little oil and diamond powder is dropped on the 
plate, it is set in motion at the rate of about two hundred 
revolutions in^a minute, and the process of grindiug down, 
and at the same time of polishing, is begun. The diamond 
is taken np and examined from time to time, and is adjusted 
so as to give the facet its true form. The heat occasioned 
by the friction is at all times pretty considerable, and when 
the pincers are heavily laden, it occasionally increases to 
such a degree as to soften the solder and displace the dia- 
mond. This is a serious accident, frequently occasioning a 
flaw in the diamond, and always fearing up the surface of 
the skive, so as to damage it very considerablyT There is 
room on the skive for tliree or four diamonds at the same 
time ; and to give each its proper share of attention, is as 
much as one person can well manage. The completion of 
a single facet often occupies some hours." 

The polish is often produced by rubbing the diamond 
with a cloth or bare hand. The form which the gems have 
to receive from the lapidary varies according to the condi- 
tion of the stones ; and the skill of the artist consists in the 
right selection of a form which shall correspond with the 
natural structure of the gems. A good cut has the greatest 
influence on the lustre and beauty of gems ; the coloi;less 
and limpid gems, for instance, require a difl*erent form from 
those which have a play of colors. With a diamond, the 
form must correspond as much as possible with its natural 
or original shape, in order to save the great trouble of 
grinding, and the waste thereby produced. Transparent 
gems ought not to be cut too thick ; the rays of light 
might otherwise be refracted too much, or prevented from 
penetrating through them at all : in the first instance, the 
lower facets do not act in correspondence with the upper, 
and the rays are much distributed before reaching the eye. 
Gems of such description are called clotty. On the other 



FOEMS OF THE DIAMOND. 161 

hand, if the gems are too thin, their beauty, elements, and 
general value are likewise diminished. There is a definite 
proportion of thickness to the breadth of colorless or limpid 
gems, whereas the cut of the colored gems depends upon 
the intensity of the color. , 

FOKMS OF THE DIAMOND. 

Diamonds were formerly cut according to their natural 
form, and mostly in the planes of the octahedron. They 
were called then point diamonds (pierres de nature, or 
pointes ingenues). 

The following forms are now, more or less, adopted by 
the Dutch and English diamond-cutters : 

A. The JBrillicmt. This cut displays to greatest advan- 
tage the lustre of the diamond : it may be considered as 
obtained by two truncated pyramids, united together by one 
common base, the upper pyramid being much more deeply 
truncated than the lower. It is formed 
— «, of the crow7i, or that part of the 
stone which remains visible after the 
stone is mounted ; 5, the collet, or lower 
part ; c, the girdle, or the common base 
for the crown and collet ; d, the table, the plane which is 
formed by the truncature of the upper pyramid ; e, the 
hisel, that space which lies between the girdle and table ; 
and f, the collet-side, the space between the girdle and 
collet. The English lapidaries cut the girdle sharp, where- 
as the Dutch leave it broad : the crowm amounts to one 
third, and the collet to tw^o thirds of the w^hole height of 
the diamond ; the table amounts to four ninths of the 
diameter of the brilliant, w^hereas the collet only needs one 
fifth of the size of the table. The table and collet are 
regular octagons, and the facets occupied by the bisel are 





162 A POPULAR TREATISE ON GEMS. 

eight lozenges, with twenty-four triangles, and are called 
the star-facets ; the facets occupied by the collet-side are 
four irregular pentagons, alternating with as many irregular 
lozenges, radiating from the collet as a centre, and are 
bordered by sixteen triangular facets adjoin- 
ing the girdle, and are generally called the 
pavilion or cross facets. According to the 
number of facets, the brilliants receive their 
names, either of double or treble brilliant : the 
double brilKant is surrounded by two rows of 
facets on the bisel, which are triangular, and 
meet each other ; the treble brilliant has fifty- 
eight planes, fifty-six facets, table and collet, thirty-two 
facets of which are in the bisel in three rows ; the star and 
pavilion facets are triangular, the intermediate, ones are 
four-sided, and on the collet-side are twenty-four facets. 

The English double brilliant consists of twenty-four 
facets, table and collet, sixteen of which terminate in the 
form of ia star in the bisel. 

Brillionets, or half-brilliants, are those diamonds, the 
spread of which is too great in proportion to their depth, 
and the crown is only cut like a brilliant, but the collet-side 
is wanting. 

B. The Rose-Diamond has a crown, 
but no collet ; it is formed of equilateral 
triangles, and consists of two rows of 
three-sided facets ; those on the girdle 
are pavilion, and the others star facets. 
But there are variations in the number of 
facets : the Dutch roses have eighteen pavilion and six star 
facets; others have six pavilion and six star facets, or 
twelve pavilion and six star facets ; and some, also, have 
twenty-four three-sided pavilion and twelve star facets. 
The rose-diamond is only that diamond, the proportion of 





FOEM or GEMS.- ^ 163 

whose breadth to its depth is too much extended, and 
which would not, without much loss, make a good brilliant. 
There are fragment rose-diamonds, which are very small, 
and ear-drop roses. • 

C. The Table-Diamond is that stone which 
is very flat and of little depth, and which re- 
flects but little lustre. They have a table with 
four planes and eight facets, and, in order to 
make the best of their lustre, they receive a brilliant cut. 

D. The JBastard-Diarriond is that diamond whose cut 
is mixed up from the above forms. 

There are a few more forms given to those diamonds 
which are found unfit for any of the above cuts, such as 
the thick-stones, the portrait-diamonds, the senail-diamonds, 
which are, however, all unfit for the above cuts. 

FORM OF GEMS. 

The gem lapidary occupies himself not only with grind- 
ing the common and rare gems, but also pastes, -^fec. He 
uses likewise wheels, but of difierent material from those 
for diamonds. His wheels are either of copper, if for very 
hard stones, or of lead or pewter for softer stones ; he has 
likewise polishing wheels. If a wheel is too soft for very 
hard stones, he cuts furrows in it, which are then filled out 
with rotten-stone or tin-ashes ; or if very hard stones, such . 
as sapphire, are to be ground, the diamond powder is 
used for the same. Tin wheels are used for hard stones ; 
water, or oil of vitriol, is used for moistening the wheels. 
The gems (in order to grind them or to give their facets) 
are cemented into a handle, at the end of which is a 
composition of resin and brickdust. Particular attention 
is required in grinding the colored gems, as the greatest 
effect may be produced by their thickness; pale-colored 
gems require to be left thicker than darker ones ; on the 



164 A POPtJLAR TREATISE ON GEMS. 

other hand, they ought nrrt to be left too thick, as they 
will appear too dark, and thereby lose their lustre. The 
same proportion in the manner of cutting the crown and 
collet of the colored gems has to be observed as with the 
brilliant ; namely, the crown ought to be one third and the 
collet two thirds in size of the depth of the whole stone ; if 
the gem be of a pale color, the collet ought to be three 
fourths of the size ; and if of a darker color, much less ; the 
table of those colored gems which require to be heightened 
ought to be waved somewhat, whereas it ought to be even 
in darker gems. The forms received by the colored gems 
in cutting resemble, in many instances, those of the dia- 
mond ; but the following are the additional ones they re- 
ceive, according to the nature of the shape and color of the 
stone : 

A. The Step or Pavilion cut. The planes, 
which are long and small, decrease towards 
the table and collet, and terminate in steps ; 
the crown has usually two, and the collet four 
or five facets on each side ; the form of the 
stones may be of four, six, eight, or twelve sides, or may 
be long or round. This cut is particularly applicable to 
colored gems, as it reflects the light in a high degree, by 
which the play of color is much raised ; and it is at all 
events to be preferred in the collet of colored gems, even 
to those brilliants in pavilion : the crown may be of any 
form whatever. 



JB, The Mixed facet cut is a com- 
pound of brilUant and pavilion cuts, the 
first being on the crown ; it is a very fa- 
vorite cut for colored gems, and con- 
tributes much in raisins; the lustre. 





FORM OF GEMS. 



165 





C. The Elongated JBrilliant facet cut, 
which, if the briUiant facets are on the 
crown elongated, and the collet has a 
pavilion cut, is very appropriate to long 
and thin stones. 

D. The Table cut, having either an uneven or 
conchoidal table, with one or two rows of facets, 
in a circular form, around it : a very useful form 
for seal-stones. 

• E. The Double facet cut, the crown hav- 
ing two rows of facets, and the collet the 
pavilion form; this cut is well adapted to 
such stones as require the concealment of 
any faults, flaws, or fissures. 

El The Cabochon cut, is either flat, convex, or double 
convex — that is, arched; it may be on both 
sides, or only on one. This cut is particularly 
applicable for semi-transparent gems, or those which display 
their peculiar colors, such as the opal, moonstone, &g. ; or 
collect the light in a small space, on one or several points, 
according to the convexity they have received. The cabo- 
chon cut may have one, two, or more rows 
of facets, and opaque stones receive with ad- 
vantage the facets over the whole surface. 
Garnets, for instance, which are generally of 
a dark color, are cut en cabochon, the lower 
plane excavated in a circular form, and the upper plane all 
around with facets. Other gems, the interior faults of 
which cannot be concealed, may be improved by this cut, 
giving them more transparency, vividness of color, and a 
greater degree of fire. • 

A judicious choice of the form in which any particular 
g-em shall be cut, depends on the skill and discrimination 
of the artist. 




166 A POPULitR TREATISE ON GEMS. 



COMMON LAPIDARY. 

Such common precious stones as are suitable to be cut 
for snuff-boxes, rings, grinding mortars, seals, and ear- 
rings, are wrought by the common lapidary, by means of 
copper or iron wheels revolving vertically. The tools are 
generally of iron, and sometimes brass ; some are flat like 
chisels, gouges, ferrules, and some others have conicular 
heads. The polish is given with rotten-stone, on a tin plate, 
or with crocus martis, on a wooden plate covered with felt. 
The cuts applied by the w^orkmen are either even, cup-shell 
form, excavated, elevated, or quite simple ; facets are not 
used by him. 

Mr. Mawe describes a lapidary's apparatus, fit for pol- 
ishing minerals, shells, <fec., and -which may be placed in a 
parlor, where every operation of polishing, on a scale suffi- 
ciently large, may be effected, and pebbles may be slit of 
three or four inches diameter. It copsists of the following 
mills : 

1st. A lead mill, or wheel, to be used with emery and 
water, for grinding down substances preparatory to pol- 
ishing. 

2d. A pewter mill, to be used with rotten-stone a little 
wet, for pohshing. 

3d. Tin plate, properly prepared, the edge of which is 
to be used with diamond powder, to slit or cut hard stones 
asunder. 

4th. Wood mills, covered with leather, &c., for polishing 
marble, alabaster, shells, or other soft substances. 

ENGRAVING. 

The value of many precious stones is increased by en- 
gravmg them. The common gems have, for several centu- 



ENGRAYING. 167 

ries, been used in heraldry. In Italy, Germany, and Eng- 
land, we find the coat of arms of distinguished or noble 
families engraved on stone. The machine used for such 
purposes is like that of the glass cutters, with this differ- 
ence, that finer and harder instruments, and sometimes 
diamond splinters, are required for this work. Before the 
stone can be cut or engraved, its surface, after having re- 
ceived the proper shape and form required, is rubbed with 
emery, glass, or leaden wheels. The artist now makes his 
drawing with a brass pin, and executes it afterwards with 
his tools. On hard stones he uses diamond powder ; on 
soft, emery and oil. 

The engraving of armorial bearings, single figures, de- 
vices, <fec., on any gem, is performed by means of a small 
iron wheel, the ends of the axis of which are received within 
two pieces of iron in a perpendicular position, that may or 
may not be closed as the operation requires ; the tools are 
fixed to. one end of the axis, and screwed firm ; the stone 
to be engraved is then held to the tool, the wheel set in 
motion by the foot, and the figure or device gradually 
formed. 

Difficult works are executed after models of plaster of 
Paris, of clay, or other substances ; the polish is afterwards 
given on wheels, provided with brushes or with rotten-stone. 
The semi-transparent and opaque stones are more used for 
engraving than the transparent gems, because the drawing 
will not show distinctly through them, on account of the 
great refraction of light ; the same is the case with irides- 
cent or shining stones. The engravings are generally bas- 
relief or raised ; those having layers are mostly preferred 
for cameos; for instance, the onyx, sardonyx, and chalce- 
dony ; also wood-opal, which is - constantly exported from 
Germany for the Italian artists in Rome. 



168 A POPULAR TKEATISE O^ST GEMS. 



SAWING AND DRILLING GEMS. 

Gems and precious stones often require to be sawed in 
different directions, which operation is performed on a 
machine like that of a lapidary, with the exception of a 
polishing jDlate, for which is substituted a cutting plate 
having sharp ends, or by fastening the stone on a stand, 
and moving continually a fine iron or copper wire stretched 
in a bow, which is moistened with emery and oil. Care 
has, however, to be taken, not to let the stone grow too 
hot, as the heat may crack or make it spotty. The Chi- 
nese use strings spun over in preference to the wire, they 
having the advantage of keeping the emery sticking to 
them, and of accelerating thereby the operation. For 
drilling gems or other precious stones, a diamond set in 
steel is made use of, to move to and fro by a bow, or the 
common engraving machine, the drilling instrument of 
which consists of an iron point, to Avhich is fastened a dia- 
mond splinter, which is pressed upon the stone while it is 
revolving upon the plate. 

• GRINDING AND POLISHING MATERIALS. 

The materials for grinding and polishing vary according 
to the hardness of the gem. The diamond pow^der is ob- 
tained by grinding real diamonds, which are unfit for use, 
with each other in a hollow cylinder of cast iron, in which 
another one exactly similar is used for the most costly and 
the hardest gems. Corundum, sapphire, topaz powder, 
and emery powder, are commonly used for grinding and 
polishing the diamond. It is well to remark that emery is 
often adulterated by a mixture of quartz and oxide of iron, 
or by garnet or iron powder. Emery fit for the use in- 
tended requires to be j^roperly pulverized and levigated. 



HEIGHTENING THE COLOR OF GEMS. 169 

According to Hawkins, the following method is pursued in 
England : The emery is pulverized in an iron mortar and 
passed through different sieves, one finer than the other ; 
the first is levigated with oil, which keeps it in better 
suspension in water ; according to the time in which the 
powder settles, the different numbers are obtained. 

For polishing the different precious stones, hard and soft 
gems, the diamond powder and emery are mostly used. 
Rotten-stone, tin-ashes, pumice-stone, oxide of iron, English 
jewellers'-red, are all used in their finest pulverized state. 
A great deal depends upon the polish which a gem has re- 
ceived ; all its other superior qualities being thereby called 
forth. 

HEIGHTENING THE COLOR OF GEMS. 

Since color is one of those characters which is the most 
tempting in the sale of gems and jewelry, all means are 
ployed for heightening the same, and covering any real 
defect. Foil of small thin metallic substances, colored or 
uncolored, either of fine silver or copper, is placed under 
the gem in the back of the mounting, which heightens the 
color and lustre, particularly of the transparent gems. 
Almost all gems were formerly set in black-colored backs, 
composed of burnt ivory-black and gum mastic, but are 
now mostly set d joiir^ which is, leaving the lower part of 
the stone uncovered in setting, and only mounting around 
the girdle — an old method, and very applicable to perfect 
stones, where no defects require con(5ealment. 

Foiling materially heightens the lustre of gems. The 
rose-diamond always requires it on account of its flat form. 
There are many gems which would not produce any effect 
without the foil ; it is therefore used whenever a pale or 
impure color is to be raised, or when the gems are to be 
protected against dust or moisture in order to produce a 



lYO A POPULAR TREATISE ON GEMS. 

uniform shade of color ; the foil forms then a suitable ap- 
plication. 

The coloring of the foil is generally performed by the 
jewellers. Isinglass,- first dissolved in water and afterwards 
boiled in spirits of wine, and then strained, is the mass or 
body to which the colors are afterwards added, which are 
also soluble in water. 

For producing a red color, the best material is carmine, 
" " . blue " " , litmus, 

" " yellow " " • saiFron. 

To produce the diiferent shades and varieties of color, the 
above are mixed in different proportions with each other. 
Yery clear stones, such as. chrysoprase, carnelian, &c., are 
sometimes painted on the back. The Paris jewellers are 
very skilful in painting stones of inferior value so as to de- 
cei^jf e even professional men ; it is for this reason that gems 
when set ought not to be purchased ; the valuable gems 
which have a foil on their back are mostly set in such a 
manner that they may be examined without the same. 
Foiled gems may likewise be distinguished by holding the 
table of the set gem on the nail of the thumb and observ- 
ing the passage of light through the crown. 

In the East, rubies are never set with foil, but a cavity is 
made in the lower part and filled with finely polished gold, 
which raises their lustre remarkably. 

Fissures, flaws, or veins, in the interior of gems, are 
mostly concealed by the foil, and when near the girdle, 
are covered by the mounting. 

The defects of stones are sometimes concealed by color- 
ing the case with mastic and ivory-black, and according to 
circumstances leaving blank the spot of the faulty stone, 
or covering only the spot, so as to produce a uniform color. 
Another, and not unusual method of concealing fissures, 
flaws, or other faults, is to cut those stones that have many 



SETTING OF GEMS. 171 

faults^ — the momentary detection of these faults being there- 
by prevented from the play of the refracting light arid the 
lustre. The color of many gems is raised by fire, which' 
acts in a peculiar manner on them ; thus the Brazilian topaz 
assumes a very fine pale-red color, by burning. The process 
of effecting this coloring is very simple, viz : after wrapping 
the topaz in a sponge, ignite the same and keep it burning 
until consumed. 

The zircon sometimes assumes a better color after having 
been subjected to a high degree of heat. Amethysts hav- 
ing, dark spots may be calcined for a short time in a cruci- 
ble containing sand and iron fihngs, under which process 
they mostly lose those faults ; but if exposed to an excess 
of heat, they will lose their color altogether, and become 
as white as quartz. The Oriental carnelian assumes, after 
burning, a fine color, and in Hindostan those carnelians 
which are found detached in the mines are cut up and 
burnt on the spot. Very fine cracks are sometimes pro- 
duced in mounting stones, which may be repaired and con- 
cealed successfully by means of garlic juice. When stones 
are broken by the same operation they may be cemented . 
by gum mastic. 

SETTING OF GEMS. 

The gems are generally fastened or set at the girdle in 
a box or rim of metal : limpid and faultless gems are always 
set a jo'ur^ i. e., without backs, since they appear then to 
the best advantage, and if the gem is intended to display 
its full size and color, the a jour setting is only fastened by 
small shanks or claws. The good setting of a gem very 
much increases its value and beauty. The material for 
mounting the limpid gems is silver, which displays them to 
more advantage than gold. In order to increase the color 
or lustre of large gems, they are often surrounded by 



1'72 A POPULAR TREATISE ON GEMS. 

smaller gems, such as small roses, rubies, emei-alds, garnets, 
turquoise, &c. 

The jewellers' wax used for mounting gems is made of 
three parts rosin, one part beeswax, and four parts fine 
brickdust. ^ . 

CLEAISING THE GEMS. 

The following composition I have found to be the best 
for thoroughly cleaning gems, particularly when set : Take 
one part flowers of sulphur and two parts of rotten-stone 
or bone-ashes, which, w^hen mixed, is used by rubbing it on 
a piece of buckskin, and with that and a stiff hair-brush, al- 
ternately rubbing the gems, finishing with a softer skin or 
cloth to remove the dust.. 

IMITATIONS OF GEMS. 

Pliny mentions the imitation of jewels by glass fluxes, 
and it is sufliciently proved that the ancients were far ad- 
vanced in this art. The Egyptian mummies were provided 
with glass buttons of green and blue color, and during the 
reign of the Roman empire, colored glass w^as A^ery general ; 
and we find antique cameos carved in various colored glass, 
representing the onyx; likewise colored glass cemented 
with real onyx ; but they never attained such perfection in 
their art as to set at defiance the skill of the artist and 
jeweller to distinguish between the genuine and spurious 
ones. The imitation of gems may be divided into three 
classes : 

A. The Pastes. The basis of these imitations is a fine, 
pure, and white glass composition, called strass^ after its 
inventor, Strass of Strasburgh, in the seventeenth century, 
who first conceived the* importance of imitating the real 
gems as respects their hardness, specific gravity, and re- 



IMITATIONS OF GEMS. 173 

fraction of light. He accomplished the task so far that in 
many instances, either all three, or one or the other of his 
objects, were attained. The strass is composed of silex 
(quartz, flint, or pure sand), potash, borax, red lead, and 
sometimes arsenic. To 300 parts of silex add 96 parts pot- 
ash, 27 parts borax (prepared from the boracic acid), and 
514 parts of white lead, and 1 part arsenic; or according 
to another method, mix 7 ounces and 24 grains of quartz 
with 10 ounces and 7^ drachms red lead, 3 ounces and 6 
drachms piire pearlashes, 3|J drachms borax, and 12 grains 
arsenic. The mixture is put into a covered Hessian cruci- 
ble, and kept at a great heat in a pottery furnace for 
twenty-four hours. The longer the mass is kept in a fluid 
state the harder and clearer it will be when turned out and 
cooled. This discolored strass is used by the lapidaries for 
imitating the diamond, rock-crystal, and white topaz. 

For imitating the colored gems various colored ingre- 
dients are employed. To obtain that intensity of color ap- 
proaching nearest to the original gem, it is experience 
alone which can guide the manufacturer. In order to imi- 
tate the uniform and intense colors, the strass coloring in- 
gredients are to be of the finest powder, and very intimately 
mixed; the mass is then to be exposed to a very great 
heat, and in that state left for nearly thirty hours, so that 
the cooling may be gradual. JSTumerous establishments in 
Germany and France are now engaged in the manufacture 
of the strass and colored pastes, each of which possesses 
secrets, acquired by experience, for producing these articles 
in the greatest perfection. 

A. Artificial Topaz. Take of perfectly white strass one 
ounce and six drachms, glass of antimony thirty-seven 
grains, and cassius purple one grain ; or add to six ounces 
of strass half a drachm of crocus martis. 

B. Artificial Huby. This may be obtained from the pre- 



174 A POPULAR TREATISE ON GEMS. 

ceding mixture for the topaz by the addition of eight parts 
more of strass, and left for thirty hours in fusion ; when 
taken out and fused before the blowpipe, it yields a most 
beautiful Oriental ruby. Five ounces strass and one drachm 
oxide of manganese may be emj^loyed for the same pur- 
pose, but will not make so fine a ruby. Or by calcining 
ammoniacal alum with chromate of potash and lampblack, 
which forms the composition of 

97 parts alumine, 

1 " oxide of chrome, 

2 " silica and lime. 

C Artificial Emerald. To one pound of strass add one 
drachm of verdigris and fifteen grains crocus martis. 

D. Artificial Sapphire. Add to eight ounces of strass 
fifty-two grains pure oxide of cobalt. 

E. Artificial Amethyst. To eight ounces of strass add* 
thirty grains oxide of manganese, twenty-four grains oxide 
of cobalt, and forty grains cassius purple ; or to one pound 
of strass, twenty grains oxide of manganese, and one grain 
oxide of cobalt. 

F. Artificial Aquamarine. To six ounces of strass add 
twenty-four grains glass of antimony, and one and a half 
grain oxide of cobalt. 

C. Artificial Syrian Garnet. To one thousand grains of 
strass add five hundred grains glass of antimony, four 
grains cassius purple, and four grains oxide of manganese. 

Messrs. Bouillette, Hyrclin & Co., Rue St. Avaye; Savany 
& Mosbach, Rue Yaucauson, in Paris; and Henrys & Co., of 
London, have contributed to the great London Exhibition, 
in 1851, a great display of their manufactures in artificial 
stones, such as diamonds, emeralds, sapphires, and pearls. 
The latter w^ere particularly brought to perfection by Mr. 
Constant Vales, Rue St. Martin, Paris, as the imitation 
pearls by that gentleman were superior to any thing the 



IMITATIONS OF GEMS. l75 

author had ever seen before, and were, to appearance, 
quite equal to the natural pearls. 

The following table, taken from Booth's Encyclopedia, 
shows the proportions of the various ingredients for the 
different colored pastes : 

Topaz. Ruby. Amethyst. Garnet. Sapphire. Aq, Mar. Emerald. 

Colorless Paste .. 1000 1000 1000 1000 1000 1000 " 1000 

Antimony Glass 40 .. .. 500 .. 7 

Oxide of Manganese.. ..25 8 4 

Gold Purple 1 . . 1/5. 4 

Oxide of Cobalt 5 .. 15 % . . 

Oxide of Copper .. .. .. .. 8 

Oxide of Chrome- . .' . . . . , . . . 1/. 

Colored glass is also very frequently cut in forms and 
shapes so as to resemble gems, and the various colors are 
.produced by melting the best qualities of glass materials 
with the following oxides : 

Yellow is produced by charcoal, antimonite of potassa, 
silver, and oxide of uranium. 

£luey by oxide of cobalt, and a mixture of copper and 
iron. ■ 

Green, by oxide of copper or of chrome, or by antimo- 
nite of potassa, litharge, and cobalt. 

Hed, by gold, suboxide of copper, and oxide of iron. 

Violet, by manganese. 

Black, by protoxide of uranium, iridium, platinum, and 
by a mixture of manganese, copper, iron, and cobalt. 

White, by oxid'e of tin, arsenic, and bone-ashes. 

By combining one or more of these oxides various shades 
and hues may be obtained ; the yellow glass of antimony 
may be shaded more into orange by the use of a little 
oxide of iron ; the purple-red of gold passes into carmine 
by employing silver with gold ; the blue of cobalt may be . 
shaded into purple by a httle gold ; into green by antimony, 



176 A. POPULAR TREATISE ON GEMS. 

or other yellow colors ; a rich grass green is obtained from 
oxide of chrome, with a little antimony and htharge ; a 
brilliant emerald-green from a mixture of oxide of uranium 
and nickel ; oxide of nickel alone yields a hyacinth-red. 

The Bohemian garnet is prepared by fusing together 100 
parts quartz, 150 parts red lead, 30 parts potash, 20 parts 
fused borax, 5 parts crude antimony, 5 parts manganese, 
and 6 parts fulminating gold ground up with oil of turpen- 
tine. 

Turquoise is imitated by oxides of copj^er and cobalt. 
Opal, by adding oxide of tin and bone-ashes to the glass, in 
small quantities. 

The following colored pastes were recommended by 
me twenty years ago, to the American manufacturers of 
colored glass, and have all proved successful : 

JStrass. 

This is the basis for all pastes ; it is very hard, and gives 
sparks when rubbed on steel. 

1 ounce of powdered glass, 2 drachms burnt borax, 

8 drachms " • quartz, 40 grains of saltpetre, 

3 " . " red lead, 30 " white arsenic. 

This composition is exposed to a white heat in a covered 
crucible for thirty hours. 

1 ounce of powdered rock-crystal 8 drachms of red lead, 

or quartz, 15 grains of cassius purple, • 
i ounce of dried carbonate soda, 8 " metallic antimony, 

4 drachms of burnt borax, 8 " oxide manganese. 
li " saltpetre. 

Or by taking — 

1 ounce of powdered rock-crystal, 40 grains saltpetre,' 
i " dry carbonate soda, 15 "■ purple cassius, 

80 grains of burnt borax, 1 drachm of .sal ammonia. 



IMITATIONS OP GEMS. 



17Y 



Take— 



Sapphire. 



li ounce of ground rock-crystal, 
6 drachms of dry soda, 

2 " ^ " borax, 

Or mix — 

1 ounce of rock-crystal, 
k " dry soda, 

3 drachms " borax, 
li " red lead. 



2 drachms of red lead, 
1 " saltpetre, 

1 grain of carbonate cobalt. 



k drachm of saltpetre, 
i grain of carbonate cobalt, 
15 " " copper. 



By means of" the carbonate of copper. 



W ounce of rock-crystal, 
6 drachms of soda, 

1 " borax. 

Take— 

li ounce of rock-crystal, 
6 drachms of dry soda, 

2 " " borax, 
2 " red lead, * 



W ounce of rock-crystal, 
\ " dry soda, 
2 drachms of dry borax, 
2 " red lead, 



9 drachms of rock-crystal, 
3 " dry soda, 

2 " red lead, 

1 " saltpetre. 



Is ounce of rock-crystal, 
i " dry soda, 

3 drachms of burnt borax, 
2 " red lead, 

20 grains of saltpetre, 



1 drachm red lead, 
h " saltpetre, 
i " carbonate of copper. 



Emerald. 



1 drachm of saltpetre, 
20 grains of red oxide of iron, 
10 " green carbotiate of 
copper. 



Green Color. 



40 grains of saltpetre, 

li " carbonate cobalt, 

10 " " chrome. 

Canary. 

80 grains of oxide of uranium, 
3 " carbonate of copper, 
• 3 " oxide of tin, 

3 " white b'nt bone-ashes, 

Chrysoprase. 

2 drachms of white bone-ashes, 
2 grains of carbonate of copper, 

4 " red oxide of iron, 



oxide of chrome. 



8» 



1*78 A POPULAR TREATISE ON GEMS. 

Opal. 

9 drachms of rock-crystal, • 15 grains of saltpetre, 

3 " dry soda, Vio " cassias purple, . 

2 " burnt borax, li " bone-ashes, 

1^ " red lead; ' 2 " muriate silver. 

Aquamarine. 

\\ ounce of rock-crystal, 1 drachm of saltpetre, 

i " dry soda, 6 grains of red oxide of iron, 

3 drachms of burnt borax, 2 " carbonate of copper. 

2 " red lead, 

Syacinth. 
The above mixture, with the addition often grains of the 
oxide of manganese. 

Garnet. 

9 drachms of rpck-crystalj 40 grains of saltpetre, 

3 " dry soda, 5 " oxide of manganese, 

2 " burnt borax, 3 " " iron, 
li " , red lead, 1 " cassius purple. 

RuhelUte^ Red Tourmaline. 

1 ounce of rock-crystal, \\ drachm of red lead, 

i " dry soda, li " saltpetre, 

3 drachms of burnt borax, 8 grains of oxide of nickel. 

lyidigolite^ or Blue Tourmaline. 
The above mixtm-e, with the addition of the carbonate 
of cobalt. 

Chrysolite. 

6 drachms of rock-crystal, 1 drachm red lead, 

2 " dry soda, ' 10 grains of saltpetre, 

1^ " burnt borax, 2 " oxide of manganese. 

Amethyst. 
But 1 grain of the oxide of manganese to each ounce of 
the mass. 



IMITATIONS OF GEMS. 179 

Turquoise. 
In the above mixture use instead of the manganese — 

5 grains of dry verdigris, 20 grains of bone-ashes. 

- 3 " powder blue, 

Lazulite. 
By adding to former mixtures, 
2 grains oxide cobalt, 1 drachm of burnt bone-ashes. 

Agate. 

By mixing together several frits and adding oxide of 
iron, several varieljes of agate are obtained. 

It will now be necessary to show the distinguishing char- 
acters between the real and artificial gems, as they so 
closely resemble each other that a superficial inspection 
will not always enable the examiner to discriminate be- 
tween them ; they are as follows : 

1. The hardness ; which may be tested on the grinding 
machine ; with fine quartz sand it will immediately attack 
the pastes, or by scmtching with a real onyx, to which the 
pastes will immediately yield. 

2. The small air-bubbles in the pastes, may more or less 
be detected with a good magnifying glass. 

3. The cold touch will never remain for any length of 
time on the pastes as it will on the real gem. 

4. The breath remains much longer on the pastes, on 
account of their bad conducting power, than on real gems. 
The specific gravity and electricity, may likewise indicate 
the difference, — but I never depended on them alone, and 
I will mention that I once examined the specific gravity of 
an artificial topaz which fully corresponded with that of a 
Brazilian topaz. Electricity, will indicate the difference 
between real and artificial gems by the length of its con- 



180 A POPULAR TREATISE ON GEMS. 

tinuance; for real gems retain, after being rubbed, their 
electricity for from six to thirty-two hom's, whereas, the 
artificial ones only retain it from forty to sixty minutes. 

JB. The Doublets. This mode of imitating real gems is 
called doubling, "when a quartz, cut and polished, is ce- 
mented by means of gum mastic to another colored paste, 
"whereby thfe whole stone assumes the color of the lower 
paste. When a real gem is employed instead of quartz (as 
the surface and the quartz or paste is cemented below), it is 
called half doiibling. This adulteration is carried on to a 
very great extent in the East Indies, where they paste any 
thin gem to a paste corresponding in color. 

The concave doiibling is effected by excavating the inside 
of a quartz or paste. The cavity being filled with a colored 
fluid, and the other j3art afterwards cemented on it, will, 
when well executed, present so uniform a color that it is 
difficult even for a judge to detect the deception. The 
surest method of detection is to put the sjiecimen in ques- 
tion in hot water or alcohol, by which the gum mastic will 
be dissolved. When set, the only way of finding out the 
adulteration, is to put it reversely on the nail of the thumb, 
when the false refraction of light or the rainbow colors will, 
with certainty, determine its identity. 

C. The Burning. This mode of adulterating the real 
gems, is performed by coloring cut and polished quartz 
specimens and throwing them into a solution of permanent 
pigments, such as a solution of indigo, decoction of cochi- 
neal, solution of ammoniacal copper ; the small cavities 
produced by the heat will absorb the fluids. The topaz is 
burnt by itself, with or without the absorption of a pig- 
ment, as also the spinelle, and the quartz ; chalcedony is, 
however, frequently burnt to imitate the onyx, and to en- 
grave thereon cameo^*and intaglios. 

It may be remarked, however, that since the introduc- 



GEMS FOE OPTICAL PUEPOSES. 181 

tioii of colored pastes, very few adulterations of this kind 
are now practised, and we see but rarely such doublets and 
burnt stones. 

PEICE OF ATSTD TEADE IN GEMS. 

It is difficult to determine the pHce of gems without 
reflecting upon all the circumstances relating to them, such 
as beauty and uniformity, the play, the lustre, and the 
vivacity of the colors, and also on the perfection of the cut, 
the polish, the rare locality, the size of the individual gems. 
It depends upon the trade of the various countries whence 
they come, and what quantity of such valuable gems may 
be had at one time at any of the great cities: we find that 
diamonds are often sold at a much less price in London 
and Patis than in Brazil. The principal trade, however, 
is as yet carried on in Brazil and the East Indies, although 
it is in no comparison so prosperous as in former years. 
The gems are sold by weight, as carat and grain. One 
carat is equal to four grains, and forty-four carats are equal 
to one ounce. The name carat is derived fj'om the word 
Jcuara^ the coral- tTee (erythrina), the red pods of which, 
when dry, were formerly used for weighing gold dust, and 
each of them weighs four grains, which is equal to one carat. 

GEMS FOE OPTICAL PUEPOSES. 

A few years ago, Messrs. Trecourt and Oberhauser laid 
before the Parisian Academy lenses of the diamond, 
sapphire, and ruby, which were used in connection with 
glass lenses in microscopes ; they were of nine-tenths milli- 
metre, in diameter. The diamond lens magnified two 
hundred and ten times, that of sapphire, two hundred and 
fifty-five times, and that of ruby, two hundred and thirty- 
five times, in linear extension. 



182 A POPULAR TREATISE ON GEMS. 

A letter was lately published from Sir David Brewster, 
on a curious optical phenomenon that had occurred in the 
construction of a diagonal lens. The diamond, previous to 
w^orking, had all the appearance of internal brilliancy ; but, 
after being polished, it presented a series of stratified 
shades, which rendered it useless for the required purpose. 
It afterwards aj^peared that lapidaries were acquainted 
with this appearance, which rendered them extremely un- 
willing to take the risk on themselves, of cutting up dia- 
monds for optical purposes. On a minute examination of 
this phenomenon, it appeared that these different shades 
occurr(id in regular strata, each section being about the 
one-hundredth part of an inch, and each stratum having a 
different focus, and being of a different degree of hardness 
and specific gravity. The inferences drawn from the above 
facts were : — that the diamond was a vegetable substance, 
and that its parts must have been held in solution and sub- 
jected to different* degrees of pressure at different stages 
pf existence. If, on the contrary, as it has been generally 
believed, it is subject to the laws of crystallization, its crys- 
tals must necessarily be homogeneous. 



PART III. 



CONSIDERATION OF THE INDIVIDUAL GEMS. 



DIAMOND. 



Diamond : Diamant (German), Adamant (of the an- 
cients), Almas (Oriental), Diamant (French). The name 
Diamond is derived from the Greek, Adamas, meaning in- 
vincible, and referring to the hardness of the gem. The 
Syrians are said to have first known the diamond, and it 
was in early ages the subject of trade to the people of the 
East. * The Carthaginians are said to have carried on their 
trade with the Etrurians, who procured diamonds from the 
interior of Africa. Pliny mentions six species of diamonds, 
among which, however, the Indian are to be considered 
the true, in contradistinction to the quartz crystals, which 
were likewise called diamonds in those times. The dia- 
mond was highly esteemed, and many medicinal virtues 
were attributed to it, particularly against mania, and as an 
antidote for poisons ; it was worn in the rough state. The 
art of cutting it with its own powder was discovered in 1476, 
by Lewis Yan Berghen. In the beginning it was cut in the 
table form, with one row of facets on the surface ; afterwards, 
in 1520, the rhomb cut was adopted: the form of brilliants 
was invented in the reign of Louis XII. Cardinal Mazarin 
was the first who had diamonds polished in this form, some 
of which yet belong *to the crown of France. For a long 



184 A POPULAR TREATISE ON GEMS. 

time philosophers vainly speculated as to the nature of the 
diamond ; first it was considered as a mineral, consisting 
of silica; but^Newton was the earliest (1675) who expressed- 
himself as to the constitution of diamonds. He judged, 
from the great refraction of light, that it must be a com- 
bustible body, and a series of experiments with it, tested 
afterwards by different naturalists, proved the same to be 
pure carbon. The first trial was made in 1694, by the 
members of the Academy at Florence, by whom diamonds 
were volatilized within the focus of a mirror. Bergman 
first classified the diamond among combustible bodies, and 
mentions having cut -ofif the head of the gems. 

Various views existed in regard to the origin of the dia- 
mond : some considered it as a secretion of a vegetable 
substance ; others as originating from volcanic or plutonic 
revolution. The Indians believe diamonds are continually 
regenerating and growing to this date ; and the inhabitants 
gf Pharrah, in Hindostan, affirm that the quantity of dia- 
monds by no means decreases, but on the contrary, the 
soil will yield a new supply fifteen or twenty years from 
the time it is exhausted. 

Numerous experiments " have been instituted to produce 
an artificial diamond from several substances which contain 
carbon, and by the application of a high degree of heat. 
The late Dr. Hare, in Philadelphia, succeeded in melting 
down mahogany charcoal so as to produce a metallic ap- 
pearance, by his deflagrator. Professor Silliman likewise 
made similar experiments with plumbago, which produced 
small globules, some of which were so transparent that they 
could not be distinguished from the genuine diamond. 
Professor Vanuxem, who examined the globules obtained 
from fused charcoal, found them to contain iron and carbon, 
which led him to the conclusion that the charcoal had not 
undergone a real fusion. Cagniard (Je Latour pretended 



DIAMOND. 185 

to have discovered the ingredients for imitating diamonds 
of some size ; but Thenard proved those small crystals of 
the appearance of diamonds to be some silicates of pecu- 
liar composition, which, according to Arago, polarized 
light in a different angle from . that of diamonds. All 
speculative experiments to imitate this most precious gem 
by the various compounds of carbon, have hitherto proved 
abortive. 

The diamond is found crystallized mostly, in the form of 
an octahedron (composed of two four-sided pyramids, united 
by their bases), or rhombic dodecahedron, rarely of a cube ; 
but the planes of the angles are often rounded or bevelled. 
The simple octahedron is pretty rare, and still more so the 
cube ; but the dodecahedron, either simple or complicated, 
is very frequent; the crystals are sometimes hemitrope. 
In the museum of the School of Mines are some fine macles, 
composed of two crystals crossing each other at right an- 
gles. The foliated passages are distinctly parallel to the 
faces of the octahedron, in which direction they may always 
be split. The fracture is conchoidal ; surface smooth, often 
rough or striped, and sometimes covered with a "scaly 
crust ; it is transparent, also semi-transparent ; of an ex- 
ceedingly vivid lustre, called the diamond or adamantine 
lustre, and when polished, of splendid fire ; it is limpid, and 
likewise passing into the greatest variety of shadings from 
white and gray, sometimes from yellow, green, and brown. 

The diamond being the hardest of all substances, yields 
to no file ; scratches all other minerals, and is not touched 
by any. This character has become the most important of 
the diamond since the late discovery of the amorphous or 
compact diamond. It is very frequently tinged light-green, 
but more rarely with orange, red, -blue, or black ; but in 
setting, these shades disappear, particularly in the smaller 
diamonds ; but there are also known diamonds of rose and 



186 A POPULAR TREATISE ON GEMS. 

pistachio-nut green colors. The blue color is very rare» 
The blue diamond of Mr. Hope, of London, is one of ex- 
treme beauty and rarity, and is of immense value ; the 
yellow diamond in the Museum of Natural History, in 
Paris, is likewise very remarkable for its color and size. 
The black diamond, which is perfectly black, although 
plainly crystaUized, occurs most frequently in small bristled 
balls, but crystalline points ; the crystals are very small, 
grouped together in an irregular manner, and extremely 
refractory to the cut ; it is considered the hardest of all 
diamonds. The green diamond is also very rare, but I 
have seen some beautiful specimens in the Jardin des 
Plantes and in Freiberg, the first in the cabinet of Abbe 
Haiiy, and the latter in the cabinet of Werner. Its streak 
powder is white or grayish ; it becomes phosphorescent by 
the rays of the sun, and electric by rubbing, which property 
it retains for half an hour; its specific gravity is 3'5-3'6 ; 
it does not alter before the blowpipe ; it burns, however, 
at a high degree of heat, and in atmospheric air with a 
bluish flame; its touch is very cold; it consists of carbon. 
The diamond bears the same name in trade, but is changed 
according to its cut ; the blackish and brownish diamonds 
are called the Savoy diamonds (Diamants Savoyards). The 
compact and amorphic diamond was first brought to notice 
by the experiments of Mr. Dufrenoy, abou^ five years ago, 
as being the transition from the .crystallized to the compact 
condition, on account of its hardness and specific gravity, 
and has become a great article of commerce ; it cuts glass, 
scratches quartz and. topaz, has a specific gravity of 3*27- 
3*52, and is completely consumed in oxygen gas; it occurs 
in kidney-shaped and irregular angular masses, but not in 
pebbles ; the exterior is generally black, sometimes resem- 
bling the graphite; somewhat resinous lustre, and fre- 
quently its form is very singular, the outside coating being 



DIAMOJS^D. 187 

black and resinous, the interior forming a crystalline ker- 
nel, vitreous and lamellar, like the diamond ; it is reduced 
to powder, and used for polishing and assisting in the cut- 
ting of the diamond. The largest specimen of the compact 
diamond weighs about 46 carats, and belongs to Mr. Hem- 
erdinger ; and a compact diamond in the Museum of Natu- 
ral History at Paris, weighing about seventeen carats, is 
valued at fifteen hundred francs. The original bed of the 
diamond is not yet known, and on this point opinions are 
much divided. In the East Indies we find it in a conglom- 
erate of sandstone, consisting of quartz grains, and disinte- 
grated by the ferruginous sand ; and in the mountain chain 
Ralla-Malla, in Hindostan, between 95° and 98° E. L. 
Some of the celebrated diamond mines consist of a breccia 
from argillaceous slate, quartz, lime, and sandstone; the 
boulders and the sand of deserts and rivers yield diamonds 
mostly rounded or in a granular form. The richest dia- 
mond mines are those of Roalcorda, at the junction of the 
rivers Bimah and Ristna; Golconda, along the shore of 
the Pennar, Sumbhulpra, and Bundelkened, in the neigh- 
borhood of Pannah, where one thousand laborers are kept 
employed. Yisapur, Hydrabad, &c., on the island of Bor- 
neo, likewise yield diamonds ; and, according to Jameson, 
diamonds were found in the Indies in the coal formation. 

In Brazil, they were discovered, in 1728,- by chance, hav- 
ing been always thrown aside with the flint and other 
refuse of the w^ashings of gold, until an inhabitant, who had 
some knowledge of rough diamonds, collected a large num- 
ber, and carried them to Portugal, and acquired by their 
sale a great fortune. Another, who was informed of the 
operations of the first, shared an equally good fortune. 
The government's attention was drawn to the matter, and 
it was declared, in 1730, that all diamonds found there 
belonged to the crown. 



188 A POPULAR TREATISE ON GEMS. 

Diamonds are found in the talcose chlorite schist, and in 
a breccia, consisting of ferruginous clay, quartz pebbles, 
sand, and oxide of iron fragments; and also in a secondary 
bed, accompanied by gold, platina, topaz, beryl, chryso- 
beryl, tourmaline, kyanite, amatose, spinelle,' corundum, 
and garnet. They are found particularly in the valley of 
Sejues, along the rivers Jequetinhonha and Pardo, which 
run into the diamond district. These carry most diamonds 
by. The dykes and brooks of the district contain more or 
less rich diamonds, which are found there in recent and 
older beds. Beyond the diamond district, the diamond is 
likewise found in the province of Minas Geraes on the Serro 
de St. Antonio, in the Serro Frio, and in the rivers Aboite, 
Andaja, da Saneno, da Prata, and several other places, 
such as the right bank of the Rio San Francisco, and 
Matto Grosso, and in the beds of Rio Pardo and Rio Vel- 
has ; in the mines of Riven and Cuithe, and all along the 
valley of Peruguado river, in the province of Bahia, in 
some of the tributaries of the Rio Doce, on the banks of 
the Cachoine. The rocks in which recently diamonds 
have been found consist of the itacolumite, a micaceous 
sandstone, accompanied by mica-schist, accidentally trav- 
ersed by quartz veins. This is the prevailing rock in the 
Serro de St. Antonio, in Avhich the Jequetinhonha rises in 
the Serro da Matta da Corda, on the eastern slope of 
which the tributaries of the Rio Francisco rise ; and in the 
diamond district of Tibagy, very rarely in the alluvials of 
ancient rocks. The gold, diamonds, and other fine stones, 
are always imbedded in the lower part- of the alluvium. 
Experience has shown the richest localities to be in Curran- 
linho, Datas, Mendanho, Cavallo-Morte, and Caxoeira de 
Inferno, where the alluvial soil is from eight to twenty 
feet thick, and is composed almost entirely of silicious 
sand, strongly colored by argillaceous iron, which forms a 



DIAMOND. 189 

species of cement of pebbles of quartz, milky quartz, and 
itacolumite, which form a coarse pudding-stone, called 
casoelho, and which is considered by the diamond-washers 
a sure sign of the diamond. Dr. Cliffe, the proprietor of a 
diamond mine in Brazil, has given much information on 
this subject. 

In Russia, .the first diamond was discovered in Juh'-, 
1829, by Humboldt and Kose, when on their journey to 
Siberia, on the west side of the Uralian mountains, in the 
gold-washing establishments of Krestowosdwisheaski, be- 
longing to Count Schuwalow. The locality, in connection 
with the other circumstances of the place where the dia- 
mond was found, bears a striking resemblance to the dia- 
mond district of Brazil. The predominating rock of the 
spot on the Uralian mountains is a quartzose chlorite, tal- 
cose schist (itacolumite), with an .admixture of iron pjn-ites 
and mica, wherein we find beds of red oxide of iron, talcose 
schist, limestone, and dolomite. In the valley of Poludenka 
and Aedephskoi the diamonds are found. among the debris 
of the mountains, accompanied by quartz, itacolumite, 
brown hematite, talcose slate, dolomite, chalcedony, ana- 
tase, gold, andplatina; it is not yet decided to what for- 
mation this rock originally belongs. The production of 
diamonds is twofold; either they are dug out from the 
earth, or they are collected in the sand of rivers. If in 
the latter way, they are more or less rounded, wedged, 
and rubbed off; whereas the former appear coated with an 
earthy, pale gray, yellow, or rose-red, rarely with a blue or 
green crust. Many valuable mines have been relinquished 
in the East Indies since the discovery of diamonds in Bra- 
zil. The locality of the finest diamonds is at present in the 
neighborhood of Sumbhulpore. Two tribes, called the 
Thata and Tora, living in sixteen villages, occupy them- 
selves particularly with searching for diamonds, beginning 



190 A POPULAR TREATISE ON GEMS. 

in the month of November, and continuing until the com- 
mencement of the rainy season, more especially in the bed 
of the Mahanudi on its left shore, where some other small 
rivers, Maund, Reloo, Eeb, <fec., empty into it. Four or 
five hundred individuals, consisting of men, women, and 
childi-en, are examining continually all the spots of the 
river from Cauderpoor to Longpoor, a distance of about 
one hundred and twenty miles, till the stjt'eam is impeded 
by the rocks ; and likewise all excavations or other cavities 
of the beds where any alluvial deposits may be traced. 
All their implements consist of a pickaxe (ankova), a board 
five feet in length, excavated three inches in the middle, 
but provided with its border (daer), and a smaller similar 
implement, called by them kootla, both of the shape of a 
shovel. The process is very simple : they first dig the 
earth with the axe, and let it accumulate in heaps along 
the shore ; the w^omen afterwards take it on their large 
shovels, and allow the water to run over the earth ; they 
then pick the flints and coarse gravel out of it, and re- 
moving the residue on smaller shovels, spread it out, and 
examine it very carefully, separating from it the diamonds 
and grains of gold. Another method pursued in the East 
Indies is to surround a small plain where the diamonds are 
expected to be found, with a wall two feet high, under 
which water is permitted to run by several openings ; after 
having thrown a good deal of earth wdthin the wall, and 
having allowed the w^ater to pass througli two or three 
times, the larger stones are picked out, the residue dned, 
and the diamonds selected as before. 

The washing establishments of the diamond in Brazil, 
particularly in the celebrated district Tejuco, on the Rio 
San Francisco and its adjoining smaller rivers, are con- 
ducted in the following manner : 

Li order to get at the bottom, or soil of the river, means 



DIAMOND. ^ 191 

are used for leading the water at a certain spot in a differ- 
ent direction, and then that part of the bed of the river is 
allowed to dry out, and the sediment consisting of a 
congl(?merate of quartz pebbles, kept together by oxide of 
iron, is brought to one place for washing. It is a large 
bench of triangular form, so as to keep from twenty to 
thirty negroes busy: in the middle of this bench is a 
gutter, with which is connected a trough, inclined some- 
what, in order that the water may run down voluntarily, 
but so that it may be stopped by putting loam at the end ; 
and another gutter with a trough is joined further down. 
The negro who has collected in the dry season a' large 
quantity of the sediment, is occupied in the' rainy season 
in putting from fifteen to eighteen pounds at a time into the 
trough, spreading it there, and allowing so much water to 
run over* it, until it runs oiF quite clear from the lower 
trough, but at the same time keeping the trough continu- 
ally moving. He then begins to pick out the larger stones 
from the earthy part, and afterwards the smaller, until 
he comes to grains, which he examines with the greatest 
care, on account of the diamonds. As soon as a negro 
has found one, he must make it known by clapping his 
hands, and the surveyor, who is seated on an elevated 
chair, so that he can oversee the work, takes and de- 
posits it in a dish filled with Avater, in which all those 
found during the day are collected. They are then de- 
livered over to the superintendent, who counts and weighs 
them, and enters the result, with other particulars, in a_ 
book kept for that purpose : he keeps them in a bag until 
he delivers ^em, which he does twice a week, to the gov- 
ernment at Tejuco. 

Every "^superintendent has to live in the neighborhood of 
the principal washing- establishments, which were formerly 
leased for a certain sum by the government ; but the im- 



192 A POPULAR TREATISE ON GEMS. 

positions practised were so great, tliat it took the siiper- 
intertdence upon its own account in 1722, and has guarded 
the diamond districts along their hues by strong sentinels, 
who will not allow strangers to. pass through without the 
permission of the general superintendent; and even the 
inhabitants, when crossing the line of the diamond districts, 
have to procure written permissions from the above au- 
thority ; and everybody must, on leaving the district, 
submit to a personal and strict examination and search by 
the soldiers ; foot-passengers are always arrested by sen- 
tinels and spies continually on the alert. St. Antonio de 
Tejuco, forty leagues from Villa Rica, is the capital of the 
dianiond district, and the seat of the superintendence of' 
the Junta Diamontina, consisting besides of a confiskal, 
two cashiers, one inspector-general, and a book-keeper. 
Ail the diamonds procured are delivered up yearly to the 
government at Rio Janeiro. 

From four to five thousand negroes were engaged in the 
years 1772 to 1775; in the year 1818 but one thousand.: 
among them were the feitores or surveyors, one hundred 
in number, in the latter year ; likewise ten superintendents, 
whose business it is to concluct the mining department and 
the collection of the diamonds. 

In order to encourage the negroes, presents of tobacco, 
cloth, &c., are awarded, according to the price of the dia- 
monds which they find ; the one who finds, for instance, an 
eighth (seventeen carats and two grains) receives his entire 
liberty ; they are severely punished for any ofience, and if 
repeated are not allowed to be at this work. Notwithstand- 
ing the most rigorous regulations and the most watchful 
attention of all the officers, the frauds in stolen diamonds 
are very considerable ; and it is estimated that the smuggling 
amounts to one third of the whole income. The smugglers, 
who are runaway slaves, examine the most remote parts of 



I 



DIAMOISTD. 193 

the district, or steal the diamonds at night from the work- 
ing establishments; others, again, who understand it, will 
take the stolen diamonds from the negroes, and devise 
means of escaping with them, either in the soles of their 
boots, or in hollow canes, &c. ; and it is a remarkable fact, 
that all diamonds obtained from the smugglers are inva- 
riably larger and more beautiful than those which are 
brought into market by the government. The thieves 
practise all manner of tricks and impositions, even in the 
presence of the surveyors : for instance, they conceal the 
good diamonds, during the washing hours, between the 
fingers, the toes, in the ears, in the mouth, or in the hair; 
they also throw them away with other stones, in order to 
pick them up in the night ; they often even swallow them. 

The soldier who arrests any smuggler, receives a reward ; 
tlie i^roperty of the latter is confiscated, and he is sent to 
Angola as a prisoner, for upwards of ten years. 

The pure transparent diamond, which is cut in the difier- 
ent forms already mentioned, loses generally one third to 
one half of its original weight by this operation. 

The following table shows the original weight of the 
rough diamonds, and that after being cut ; viz. : 

Eegent, when rough, weighed 410 carats, and when cut, 136'Vi8 carats. 

Grand Mogul, " " 78OV2 " " 279 s/jg " 

Ko-lii-noor, •' " I86V2 " " 82i2/]s " 

South Star, " " 254'/2 " " 124 Yig " 

Nassak, once cut, " 893/4 " " V8i"/i8 " 

It will be perceived, therefore, that the skill of the dia- 
mond-cutter has made great progress in modern times, in- 
asmuch as the weight of the Ko-hi-noor and South Star 
was only reduced to one half of the original weight. 

In purchasing rough diamonds, every precaution ought 
to be used to prevent getting false diamonds instead of 

9 



194 A POPULAR TREATISE ON GEMS. 

real ones, and faulty ones instead of pure diamonds. The 
officers of the Junta Diamontina test the rough stones by 
holding them whilst rubbing together, close to the ear, and 
listening to the tone produced, which gives them ample 
satisfaction of their being genuine, as it is only to be ob- 
served in real diamonds. It requires, however, consider- 
able practice to distinguish them with accuracy by this test. 
Strangers particularly, are imposed upon by the negroes 
in Brazil, by purchasing from them gems cut and polished 
with the facets, resembling, those of the diamond ; and 
although any one acquainted with the diamond will soon 
detect the imposition by the want of specific weight, the 
peculiar lustre, fire, and hardness, he requires to be on his 
guard. If, however, the diamond is ascertained to be 
genuine, we have to examine particularly its purity, color, 
form, and size, these being the qualities by which the price 
of a rough diamond is to be determined. 

It requires considerable experience to determine from a 
rough diamond whether any of its faults are at the surface 
or in the interior, whereby often the diamond, in removing 
all its faults, may be diminished to half its size. We Often, 

« 

however, judge the rough stones by their color ; those 
turning towards the green color are considered to be the 
best; those of a reddish color to be good stones; the black 
color indicates a hard stone ; and we judge a yellowish or 
grayish color as making bad diamonds. The natural form 
of a diamond, likewise, gives a characteristic to the pur- 
chaser of rough stones ; for a flat, thin, or triangular stone 
would lose much in the grinding, and not be so high as to 
give it sufficient fire ; and likewise we are not sure of the 
result of the cutting, and the hemitrope crystals are very 
difficult to work. The best forms of diamonds for cutting 
are the octahedron, which is principally found in the East 
Indies, and is called Pint by the diamond-grinders ; and the 



DIAMOND. 195 

rhombic dodecahedron, which is found principally in Brazil : 
cheese-stones is the name given to amorphous diamonds by 
the diamond-grinders. 

According to the quality of the diamonds, they are 
divided in Sumbhulpurinto four classes, which correspond 
with 'the deities of- the Hindoos — the Bramins, Tschettri, 
Wassiers (Bysh), and Tschadrie. The native jewellers are 
very expert in estimating the value of these diamonds. 

The value of the polished diamonds depends on the fol- 
lowing conditions : 

1st. Color. The limpid diamonds command the high- 
est price, and twice as much as those that are colored; 
the blackish, brownish, yellowish, brown, steel-gray, and 
impure bluish ones, stand in no value, and are often rejected 
for working. " 

2d. Purity., Faidtlessness., and Transparency. The dia- 
monds ought to be, according to the technical terms of 
the jewellers, free from ashes, gray spots, rusty or knotty 
places, veins, fissures, scratches, feathers, flaws, sand, grains, 
and flint yellow or vitreous spots. The Brazilian diamonds 
exhibit sometimes, in their interior, designs resembling 
mosses, like those of the Mocha stones and agates ; and we 
may often observe it in the green diamond ; if a limpid 
diamond plays somewhat in the brown color, it is called 
shrugging., and this diminishes its value : paunched., are 
those diamonds which are neither pure nor clear. 

The transparency and clearness of the diamond are di- 
vided into three degrees, viz : 

A, of the first icater., as in those diamonds which are free 
from even the slightest faults, and stand highest in price. 

B, of the second water., as in those diamonds which, 
although clear and limpid, are marred by some dark spots, 
clouds, or flaws. 

C, of the third water., as in those diamonds having a 



196 A POPULAR TREATISE ON GEMS. 

gray, brown, yellow, green, blue, or blackish color;, or 
those that are Umpid, but are injured by several material 
faults. 

In order to determine accurately the nature of diamonds, 
it is well to breathe on them, whereby they lose for a mo- 
ment their lustre, and the eye is then better enabled to 
examine them and distinguish their faults. The real dia- 
mond becomes clear much sooner than the false. 

3d. The Cut. The perfect and regular cut of the dia^ 
mond increases its value considerably ; a brilhant, for in- 
stance, of one carat, is worth twice' as much as a rough 
diamond of equal weight. It depends upon the proportions 
of the height to the circumference of the diamond, and 
that the planes and facets stand in a regular proportion, for 
should this not be the case, the diamond would lose much 
/ of its fire. Likewise, the form of the diamond influences 
■ the price. A brilliant is dearer than a rose-diamond, and 
this a2:ain is dearer than the thick and table-stone. The 
facets of the brilliant also influence the price : once cut is a 
brilhant that possesses no cross-facets on the lower part of 
the stone ; twice cut^ there is one row of facets on the collet 
side; thrice cut^ the brilliant possesses the facets on the 
bizel and collet side, according to the rule of cutting. The 
more rows of facets a brilliant displays, the higher price is 
put upon it. 

4th. The Size and Weight. The price of a diamond de- 
pends considerably upon its size ; those diamonds which 
are of great splendor and size are called Paragons or Non- 
pareils, the Ne Plus Ultra; the less weighty ones are 
valued according to their actual weight. The weight em- 
ployed in Sumbhulpur is the rutta and masha. Seven rutts 
is equal to one mash, and one rutt is equal to two grains. 
In Brazil the weight is specified by carats (quilates). 
Seventeen and a half quilates are equal to one drachm (oc- 



I 



DIAMOND. 197 

tava) ; thirty-two vintenes are equal to seventy grains 
(graos) ; one carat is equal to four grains. 

The price of diamonds is determined in trade by exam- 
ining accurately their character as above stated, and then 
the price is fixed ; the weight of the diamond is at first 
multiplied by itself, and the sum obtained multiplied again 
by the price of one carat. A brilliant, for instance, would 
weigh two carats, and on examining its properties, if good, 
its price would be found to be forty-four francs. We pro- 
ceed in the following manner to get at the full value of the 
diamond : 2X2X44 = 176 francs.. We do not always, how- 
ever, arrive at the correct result. If the brilliants are very 
large, and exceed the weight of eight or ten carats, it is 
difficult to arrive at a standard. I will endeavor to give 
below a table of the prices of the diamond in Holland, 
France, England, Germany, and the United States, as far 
as ascertained, and as near to the actual price current as I 
could obtain. 

Rough diamonds fit for cutting are worth ten or twelve 
francs per carat ; any diamond exceeding the weight of one 
carat is estimated by the square of its weight multiplied 
by eleven or twelve francs as the average price. 

Eo»e-diaraonds of first water and one carat, - - 20 francs. 

" second " " - - 18. 

Table-stone, -- - - - - - - 14 

Brilliants, 30 to 85 pieces to the carat, - - - 22 

" 20 " " " _ _ - 40 

" 10 *" " " - - - 88 

" 5 " " " _ _ - 85 

" 4 " * " " - - - 86 

Brilliants of three grains are in mucb demand, and are' 
worth fifty francs j)er carat. Those of three carats, used 
for centre-pieces in necklaces, are sometimes worth four 
hundred francs. Rose-diamonds for mounting, and forty 



198 



A POPULAR TREATISE ON GEMS. 



to the carat, are worth twenty francs the carat; if a little 
larger, thirty-five francs per carat. 

Diamonds unfit for cutting, and used by glass-cutters or , 
glaziers, are worth from ten to fifteen francs per carat, and 
still smaller ones are worth less ; they are now employed 
by lithographers for their engravings and etchings. 

In 1837, according to Netot, Pujoux, and Lucas, the 
price of diamonds of the first water was three hundred 
francs per carat ; and second water, one hundred and fifty. 



Diamonds of one grain and less^ 
The double cut, first water, 

" 6 to a grain, 

Of two grains, _ _ - . 
Of three grains, - - - • 
Of one carat, _ _ - . 
A diamond of 6 grains, 

u 8 *' - ■ 

" 10 " - ■ 

" 12 " - - 

" 15 " - • 

« -18 " 

" of 6 carats, 



96 francs per carat. 
125 " 



- 150 

- 170 

- 200 
260-280 

- 600 

- 1000 

- 1400 

- 1800 

- 2400 

- 3500 

- 5000 



The above prices are from Brard's Mineralogie appliquee 
aux Arts. 

The price of diamonds (in 1855), according to Mr. 
Achard, a celebrated dealer in Paris : 

Glass-cutters' diamonds, less than a grain, 50 francs, or $10 00 per carat. 
Diamonds to reduce to powder, - - 12 " 2 50 " 



These are the natural diamonds. 

Diamond powder for polishing, 
Compact diamond, called carbonite, 
" in powder, 

Diamonds of 1 carat are worth - 
(( 3 " " 



8 francs, or $1 75 per carat. 
- 4-6 ■" 1 50 " 

6 " ] 5Q " 

250 francs, or $50 00 
800 " 160 00 

- 1,500 " 300 00 

- 10,000 " 2000 00 



DIAMOND. 



199 



According to Barbot, the present (1858) price current of 
diamonds of good quality, and in relation to their weight 
and various forms, is the following : 



A diamond 


of 1 carat is worth, per carat, 


800 fr< 


mcs, 


or $60 00 




8 grains " " 


240 




48 00 




2 (( (' u 


210 




42 00 




r-l 


180 




86 00 




recut, S to the carat, " 


180 




86 00- 




U IQ u u u 


190 




88 00 




not recut j 8 to the carat, " 


140 




28 00 




" 16 " " 


150 




'80 00 




u 20 " " 


160 




32 00 



EOSES FROM HOLLAND. 

A rose of 1 carat is worth, per carat, - 200 francs, or $40 00 

" 3 grains " " - 170 " 84 00 

" 2 " " " - 160 " 82 00 

" 1 . " ." " - 140 " . 28 00 

A rose of 8 to the carat " - 160 " 82 00 

" 16 " '■' ■ - 165 " 88 00 

" 50 " " ■ - 180 " 86 00 ■ 

" 100 " " - 200 " 40 00 

If 2-500 stones to the carat, they are sold, on an average, 
in quantities, at one franc twenty centimes, or twenty-five 
cents, per piece; if 1000 to the carat,- twelve and a half 
cents, per piece. In Antwerp the roses are sold at one 
hundred francs per carat, and from two grains upward 
they are sold, when mixed in quantities, at sixty to eighty 
francs per carat. 

In the United States, the price of diamonds, in 1859, de- 
pending on their perfection, is about the following : 

1 carat stones, - - - - - - $85 to $100 per carat. 

3/4 '' ------ 70 80 " 

Melee or mixed stones, from i/g to % carat 
stones, ------- 50 60 ." 

Vi carat stones the same as the melee. 

V2 " from $10 to $15 more than the melee stones. 



200 A POPULAR TREATISE ON GEMS. 

A good white and 'perfect diamond of two carats 

weight is worth from _ _ _ _ _ $300 to $350 

A 3 carat stone, 500 600 

4 " ------.- 900 1000 

5" _-_-___ 1000 1200 

Spread diamonds, meaning flat stones, so as to display a 
large surface, whereby the collet is shorter than the crown, 
are generally sold, much cheaper ; they do not, however, 
display their elements with the brilliancy of a diamond 
having two thirds of the collet and one third of the crown 
in size. 

At a most extensive sale of diamonds, which took place 
in the summer of 1837, at the auction of Rundell & 
Bridges, London, there were twenty-four lots put up, 
which produced the sum of forty-five thousand eight 
hundred and eighteen pounds^ nearly two hundred and 
tioenty-nine thousand dollars ! Some of the prices were 
as follows : The celebrated Nassak Diamond, which weighs 
three hundred and fifty-seven and a half grains, and is of 
the purest water, was purchased for thirty-six thousand 
dollars. It is considered to have been sold at a price con- 
siderably under its value. A magnificent pair of brilliant 
ear-rings, weighing two hundred twenty-three and a half 
grains, formerly the property of Queen Charlotte, were 
bought for fifty-five thousand dollars, a price infinitely be- 
low their usually estimated value. A sapphire, seventy-five 
and a half carats, set with briUiants for a brooch, two thou- 
sand four hundred and sixty-five dollars. Brilliant ear- 
rings, three thousand seven hundred and fifty dollars. A 
brilliant necklace, four thousand three hundred dollars. 
Drop emerald ear-rings, two thousand three hundred and 
twenty-five dollars. Brilliant ear-rings, four thousand two 
hundred and fifty dollars. A Turkish dagger, mounted 
with brilliants and rubies, four thousand dollars. A single 



DIAMOISTD. 201 

brilliant, eight hundred dollars. A brilliant drop, seventy- 
nine and a half grains, five thousand nine hundred dollars. 
An oblong brilliant, one hundred fifty-one and a quarter 
grains, fourteen thousand dollars. A brilliant necklace, 
eig-ht thousand dollars. Brilliant ear-rin2:s, twelve thousand 
five hundred dollars. Brilliant necklace, twelve thousand 
five hundred dollars. Brilliant drops, formerly belonging 
to Marie Antoinette, eight thousand eight hundred and 
seventy-five dollars. A rose-diamond, eight thousand five 
hundred dollars. A brilliant drop, ten thousand five hun- 
dred dollars. A round brilliant, seventeen thousand five 
hundred dollars. A lozenge brilliant, three thousand five 
hundred dollars, &g. 

Frauds in diamonds are practised by dealers, and the 
purchaser must be guarded. The white spinelle crystal- 
lizes also in regular octahedrons, but is not as hard, and is 
therefore scratched by the diamond. The angle under 
which the light is polarized in either of the other gems is 
very different. 

On com23arison with the prices of those now in market, 
it is certain they have much declined, which is partially to 
be attributed to the immense stock which has been brouo^ht 
from their native locality. According to Spix and Martins, 
there have been produced in Brazil, from 177^ to 1818, 
1,298,037 carats of diamonds — that is, in the time of the 
Royal Administration ; but that during the Lease, only 
1,700,000 carats were produced, which together make 
2,998,087 carats, or 1301^ pounds, thus averaging from 
fourteen to fifi^een pounds per year*; those brought into 
market by contraband being excepted. The value of the 
above diamonds (8000 reis jDer carat), produced in Brazil, 
amounts to 23,984,276,000 reis, or about 40,000,000 francs. 
This sum bears no comparison to the expense of procuring 
them, since the governnjent lately paid forty francs fifty 



202 A POPULAR TREATISE ON GEMS. 

centimes per carat, whereas they only yielded from eight- 
een to nineteen francs. On this account the administration 
at Rio de Janeiro has been induced to lease the mines to 
private individuals. Owhig to this decrease in the produc- ^ 
tion, the number of laborers is i*educed. The richest pro- 
duction was in 1784, when 56,145 carats were washed out ; 
and the poorest in 1818, when they procured but 9396 
carats. In Brazil, large diamonds are much rarer than in 
the East Indies, where they are in general of much better 
quality than in Brazil. In the latter country, from 1772 to 
1811, they found but thirty-six diamonds weighing upward 
of seventeen carats, and from 1812 to- 1818, but eighty- 
three diamonds weio-hino; over eisrht carats. In the East 
Indies, according to Breton, from the year 1804 to 1818, 
there were found in Mahanues twenty large diamonds, the 
aggregate weight of which amounted to four hundred and 
thirty-six carats and one grain. The largest was found in 
1809, and weighed six hundred and seventy-tAVO grains, 
but was of the third water ; another of three hundred and 
eight grains, and another of two hundred and eighty-eight 
grains. 

As it has already been stated that the artist and amateur 
have to be on their guard against imposition in the purchase 
of diamoi^ds, it may be well to state that there is the one- 
half brilliant, having the form of a brilliant above (the 
upper pyramid), but no lower pyramid ; or another stone 
is pasted on by means of mastic. The character of the 
stone is readily detected when taken out of the mounting. 

Sappljires, hyacinths, emeralds, and topazes are some- 
times slightly calcined and sold for diamonds. The first 
two are heavier than the diamond ; they are, however, 
harder, and possess more fire. The topaz is distinguished 
by its property of becoming electric when heated, which 
lasts for several hours. 



DIA^MOND. 203 

Rock-crystal is much lighter, but brilliant and hard ; and 
the same character is applicable to the strass. 

The following list shows the size and w^eight of the most 
interesting diamonds in the possession of different sover- 
eigns. 

The largest diamond is in the possession of the Grand 
Mogul, and according to Tavernier, resembles in form and 
size, half a hen's egg. Its weight is two hundred and 
ninety-seven and three sixteenths carats. It w^as found in 
1552, in the mine of Colore, a short distance to the east of 
Golconda, and is valued at. 11,723,000 francs. It is cut 
as a rose-diamond, and is perfectly limpid, with the excep- 
tion of a small flaw at the end of the girdle. 

The diamond in the possession of the Rajah of Mattan, 
in Borneo, w^eighs three hundred and sixty-seven carats : it 
was found on that island. It is of an egg form, has 
a cavity towards the thinner end, and is .of the first 
water. 

The Orlow, the diamond belonging formerly to ISTadir 
Shah, sultan of Persia, and now in possession of the Rus- 
sian crown, weighs one hundred ninety-four and three 
fourths carats. It is of the first water, without flaws or 
faults of any kind. Its form is that of a flattened oval, 
about the size of a pigeon's egg — it formed the eye of a 
Braminian god — cut in a pyramidal form ; it is one inch 
three lines in diameter, and ten lines high. It was pur- 
chased by the Empress Catharine for about ninety thousand 
pounds, cash, and an annuity of four thousand pounds, but 
is considered of more value. 

The diamond in the treasury of Rio Janeiro, was found 
in 1771, at Rio Abaite, by three criminals, who delivered 
it to the government, for which they were pardoned. It 
weighs one hundred and thirty-eight and a half carats. 

The Austrian crown possesses one which weighs one hun- 



204 A POPULAR TKEATISE ON GEMS. 

dred and thirty-nine and a half carats, and is valued at one 
hundred and nine thousand two hundred and fifty pounds. 
It is beautiful and well formed, but its color turns towards 
the yellow. 

There is another belonging to the crown, which was 
formerly in the possession of Charles the Bold, of Bur- 
gundy, who lost his all in the battle of Granson. This 
diamond was at that time the largest in Europe. A 
Swiss soldier, who ^yas the robber thereof, sold it for a 
crown dollar to a priest ; and after passing through several 
hands, it was purchased by Pope Julian II. for twenty 
thousand ducats. 

The Regent^ or Pitt diamond, belonging to the crown 
of France, is said to have been found in Malacca, and was 
purchased by Mr. Pitt, then governor of Bencooleri, in 
Sumatra, and sold by him to the Regent, duke of Orleans, 
by whom it»was placed among the crown-jewels of France. 
It weighs one hundred and thirty-six and three quarters 
carats ; is cut in the form of a brilliant, and is of the first 
water, being absolutely faultless. When rough, it weighed 
four hundred and ten carats, required two years' labor in 
cutting, and is worth, according to the value put by the 
commission of jewellers, in 1791, twelve millions of livres. 
It was much admired in the exhibition of Paris, in 1855, 
among the crown-jewels of France. 

The Sancy^ belonging to the crown of France, is one of 
the celebrated diamonds, although not as large as the last . 
mentioned, still a very beautiful stone ; it is of a pear-shape, 
is cut as a double rose-diamond of an oblong figure, and 
weighs fifty-six and a half carats (thirty-three and twelve 
sixteenths, according to Barbot), and it cost (300,000 livres, 
but is now valued at double that sum. 

A very curious history is attached to this stone, which 
may not be uninteresting to the reader, for its peregrina- 



DIAMOND. 205 

tions are wonderful and are well worth relating. At first 
it was seen glistening in the casket of Charles the Bold, 
the last duke of Burgundy, who lost it in the battle of 
Granson; it was found by a Swiss, who sold it to a jDriest 
for two francs, he resold it for three francs ; it is then lost 
sight of until in the year 1589, King Anthony, of Portu- 
gal, pledged the same among other stones to M. de Sancy, 
then Treasurer of the King of France, who retained it by 
paying 100,000 francs for it. Henry III., after a lapse of 
time, borrowed it- for the purpose of pledging it to the 
Swiss government, but the servant that was to convey it 
to that country disappeared, and was not heard of for a 
long time ; at last it was discovered that the messenger 
was assassinated by thieves ; but the faithful servant rather 
than deliver the jewel to the thieves preferred swallowing . 
it. The spot where the body was interred was discovered ; 
being disinterred, on dissecting the stomach the diamond 
was found. The Baron de Sancy disposed of it to James 
II., while at St. Germains, and from him it fell into the 
hands of Louis XIY. for 625,000 francs, and has ever since 
been the property of the crown of France. The same 
stone was lost in 1792, with the greater part of the other 
jewels : it was found again by the police in the Champs- 
Elysees, through an anonymous letter. 

The Regent, the blue diamond, the celebrated onyx 
known by the name of Abbe Sugen's communion-cup, with 
other diamonds to the value of several millions of francs, 
were then stolen, and but few of them recovered. 

The blue diamond of the crown-jewels of France, is of 
a rich sky-blue color, and weighs sixty-seven and one eighth 
carats ; it was valued at 3,000,000 francs, but was stolen 
among the other jewels, in 1792, and not recovered. It is 
said, however, that it was sold in 1835, by an agent of the 
Bourbon family, to a purveyor of the Emperor of Russia, 



206 A POPULAR TREATISE ON GEMS. 

for the sum of 500,000 silver roubles ; since which time it 
has been in the hands of the Princess Paul Demidoff. 

Russia is said to be the richest country for diamonds; 
her crowns are of immense value ; that of Ivan Alexiowitch 
contained 881 brilliants ; that of Peter the Great, 847 ; that 
of Catharine, 2536, and the jDresent emperor has purchased 
for his crown an immense amount of brilliants. 

The Shah is another of the great diamonds belongi-ng to 
the Russiafi crown ; it is an irregular prism, of fine water, 
and weighs ninety-three carats; it belonged formerly to 
the Emperor of Persia, and then to Nadir-Shah, and was 
stolen by the revolting soldiers. 

The Polar Star belongs to the Princess Youssoupoif, is 
cut into a brilliant, and weighs forty carats. 

The Prince Esterhazy, as colonel of a fine regiment in 
the service of Austria, wears, in his uniform of state, a dia- 
mond valued at twelve millions of francs. 

The Pacha of Egypt has a diamond cut in facets, which 
weighs forty carats, and cost 700,000 francs. 

The Piggot weighs eighty-two and a half carats ; is not 
very fine ; was sold by lottery, in 1801, for 750,000 francs, 
and belonged, in 1818, to the jewellers Rundell &> Bridges. 

The Nassak belonged formerly to the East India Com- 
pany; weighs eighty-nine and three quarters carats; has 
since been recut by order of the Marquis of Westminster ; 
weighs at present but seventy-eight and five eighths carats, 
and is valued at 800,000 francs. 

The Holland Dia'mond weighs thirty-six carats, and is 
valued at 260,000 francs. 

The Hope Diamond^ which weighs forty-four and one 
eighth carats, is of a beautiful color like sapphire ; is sus- 
pected of being the same stone which was stolen among the 
French jewels, in 1792. Owmg to its beauty it was pur- 
chased for 450,000 francs, but is worth more. 

i 



DIAMOND. 207 

The Dresden Treasury has a beautiful green diamond, 
like emerald, which weighs thirty-one and one quarter 
carats. 

The value of the crown-jewels of France, has always 
been 29,000,000 francs; among them are comprised — 

Diamonds 16,730,203 francs; 

Pearls (506 in number) , 996,700 " 

Colored Stones — 

230 Eubies " 

134 Sapphires 

150 Emeralds 

71 Topazes : !► 860,604 " 

8 Amethysts (Oriental) ', 

8 Syrian Garnets 

8 Other fine stones 

Mounted jewelry 5,834,490 

Ornaments and trinkets 5,144,390 



Total 29,066,487 *' 

The great treasures which were stolen on the 1 7th Sep- 
tember, 1792, and not recovered, contained over 1000 
carats of brilliants and roses of various sizes and qualities. 
In 1810 the Emperor Napoleon I., after purchasing over 
the Continent all the diamonds and jewels which were 
formerly stolen from the treasury, had another inventory 
made out. 

A very' black diamond, which belonged to Mr. Papst, 
who sold it to Louis XVIII. for 24,000 francs; it is of 
dark-brown color, but a fine lustre. It came from the 
collection of Dagni ; but it is not known what has become 
of it. 

A fine rose-diamond of fifteen carats, in the possession 
of Prince Rioria, at Naples, in 1830. 

Mr. Halphen owned a diamond, in 1838, of twenty-two 
and one half carats weight, of a magnificent and rare 
water. 



208 A POPULAR TREATISE ON GEMS. 

The Nizam belonging to the King of Golconda, is a 
magnificent rough diamond ; it weighs 340 carats, and is 
vahied at 5,000,000 francs. 

There are two rough diamonds, belonging to the King 
of Portugal, one of which weighs 215 carats; they were 
found in the river Abayte, which runs through the Province 
of Minas Geraes, in Brazil. * 

A magnificent pyramidal cut diamond, in Brazil, is 
valued at 872,000 francs. 

A rough diamond, found in the river Abatio in Brazil, is 
in the possession of the Prince Regent of Portugal, which 
weighs an ounce Troy. 

The two large diamonds belonging to the Shah of Persia 
have already been mentione(i in the first part, with accom- 
panying figures. 

The Turkish crown has two very large diamonds ; one 
of eighty-four carats, and the other of one hundred and 
forty-seven carats. The latter is valued at eighty thousand 
ducats. 

One found in Brazil, in 1780, weighs seventy-two carats 
and three fourths of a grain. Another, found in 1803, 
weighs seventy carats. They are both at Rio Janeiro. 

The largest of all known diamonds is said to be in the 
possession of the King of Portugal. It was found in Bra- 
zil, in the diamond district, and is as yet in its rough state. 
It is of the size of a chicken's ^^^^ weighing one thousand 
six hundred and eighty carats (above eleven ounces), and 
is estimated in value at fifty-seven million pounds sterling. 
It is now the general opinion of jewellers and mineralogists 
that this is a white topaz. 

The Koh-i-noor^ of which there is an exact representation 
on the frontispiece of this work, in its present form, belongs 
to the Queen of England ; it is translated as the Mountain 
of Light, and is a very remarkable gem, both for its size as 



DIAMOND. 209 

well as its history. It belonged formerly to the Grand 
Mogul, from whom it passed into the hands of the sover- 
eigns of Cabul. Rnnjeet Sing, the king of Lahore, be- 
came possessed of it in 1813, after a victorious war against 
the Shah Shuja. At the death of Runjeet Sing, the East 
India Company took possession of his estates, and this relic 
fell into their hands, and by the latter was presented to 
the Queen of England. Its original weight was one hun- 
dred and eighty-six carats ; it was of an elongated form, 
Avhich led to the supposition that it is a part of an octahe- 
dral crystal ; this opinion has been repeatedly expressed, 
and more particularly by Mr. Tennant, who believes it to 
be a fragment of the Grand Mogul's diamond described by 
Tavernier. Its awkward shape and bad polish induced the 
queen to have it recut, which was done by Mr. GaworcJ, 
who gave the Koh-i-noor the form of the Regent Diamond, 
and lost thereby nearly one third of its original weight. 
It is now a beautiful diamond, and is valued at two millions 
of pounds sterling. 

The Star of the South, a Brazilian diamond, found in 
July, 1853, is at the present day the largest in Europe, 
coming from Brazil. It belongs to Mr. Halphen, a private 
gentleman, and weighs two hundred fifty-four and a half 
carats ; as a crystal, was a dodecahedron ; it has a specific 
gravity of 3*529. On account of a deep cavity of an octa- 
hedric form, by which it appears to have been attached, at 
a previous stage, to another crystal, it is ascertained by the 
French lapidaries that this diamond will jiose nearly half its 
weight, so that after being cut and faceted, it will weigh 
about one hundred and twenty-five carats, but will still 
rank as a princely diamond. It was found by a negress 
employed in the mines of Begagem, one of the diamond 
districts in the province of Minas Geraes. 

Another large Brazilian diamond was found in the river 



210 A POPULAR TREATISE ON GEMS. 

Abaite, and is said to weigh about one hundred and twenty 
carats. 

The JVccssak diamond belongs to the East India Com- 
pany, and weighs eigKty-nine carats. A beautiful green 
diamond is shown in the royal collection (grtine gewolbe), 
weighing forty-eight carats. • 

Among the American diamonds maybe mentioned one 
in the possession of Capt. Dewey, having been found in 
Virginia, and a perfect crystal — a rhomboidal dodecahe- 
dron, with curved faces, of greenish-white color, and per- 
fectly transparent — weighing about twenty-five carats. It 
reflects strongly the light, and has a brilliant adamantine 
lustre. Smaller diamonds have been found in Alabama, 
three of which belong to Mr. Barnett Phillips of Philadel- 
phia, weighing one, two, and three carats respectively, and 
likewise perfect octahedrons. In Rutherford ' County, 
North Carolina, a diamond of one and a half carats was in 
the possession of Mr. T. G. Glemson. In Hall County, 
Georgia, diamonds have been found several times ; in Cali- 
fornia some diamonds are said to have been found. 

The black diamond, which has lately been found in 
Mexico, in the Sierra Madre, is also attracting the atten- 
tion of lapidaries, being harder than any other diamond. 

Description of the Crown-Jeioels of Queen Victoria Z, 
worn at her Coronation^ 2^th June^ 1838. 

The crown in which her majesty appeared at the cere- 
mony of the coronation was made by Messrs. Rundell & 
Bridges.* It is exceedingly costly and elegant ; the design 
. is much more tasty than that of the crown of George IV. 
and WilHam IV., wJiich has been broken up. The old 
crown, made for the former of these monarchs, weighed 
upwards of seven pounds, and was much too large for the 



DIAMOND. 211 

head of her present majesty. The new crown weighs httle 
more than three pounds. It is composed of hoops of silver, 
inclosing a cap of deep purple, or rather blue, velvet ; the 
hoops are completely covered with precious stones, sur- 
mounted tsdth a ball, covered with small diamonds, and 
having a Maltese cross of brilliants on the top of it. 

The cross has in its centre a splendid sapphire ; the rim 
of the crown is clustered with brilliants, and ornamented 
with fleurs-de-lis and Maltese crosses equally rich. In the 
front of the Maltese cross which is in front of the crown is 
the enormous heart-shaped ruby, once worn by the chival- 
rous Edward the Black Prince, but now destined to adorn 
the 'head of a virgin queen. Beneath this, in a circular 
rim, is an immense oblong sapphire. There are many 
other precious gems, emeralds, rubies, and sapphires, and 
several small clusters of drop pearls. The lower- part of 
the crown is surrounded with ermine. It is, upon the 
whole, a most dazzling and splendid crown, and. does infi- 
nite credit to those by whom it has been designed and put 
together. Her majesty has expressed herself highly pleased 
with it. 

The following is an estimate of the value of the jewels: 

20 diamonds round the circle, £1500 each £30,000 

2 large centre diamonds, £2000 each.-. 4,000 

54 smaller diamonds placed at the angles of the former. . . 100 

4 crosses, each composed of 25 diamonds 12,000 

4 large diamonds on the tops of the crosses ' 40,000 

18 diamonds contained in the fleur-de-lis '. . . . 10,000 

18 smaller diamonds contained in the same. 2,000 

Pearls, diamonds, &e., on the arches and crosses 10,000 

141 diamonds on the mound 500 

26 diamonds on the upper cross. ' 3,000 

2 circles of pearls about the rim 800 

£111,000 
The following list of jewelry exhibited at the London 



212 A POPULAE TREATISE ON GEMS. 

Industrial Exhibition, in 1851, by some French and Eng- 
lish manufacturers, comprises but a small part of the im- 
mensely valuable treasures therein collected : The Queen 
of Spain allowed the manufacturer, Mr. G. Lemonnier, of 
Paris, to show two sets of her jewels. The first consisted 
of a diamond necklace, in the form of a ribbon, interlaced 
with foliage of emeralds; the stomacher ahd shoulder 
knots, from which were suspended very large emeralds, 
with clusters of brilliants. A bouquet was formed of lilies 
of brilliants, the leaves of emeralds, and ribbons of brilliants 
with pendants of pearls. The crown was in the same style, 
with aiguillettes in the form of flowers, having stamens in 
pearls. The bracelet was likemse a ribbon of brilliants, 
interlaced with emeralds. Another set of jewels, made 
entirely of diamonds and sapphires ; the crown, composed 
in the heraldic style, held in the centre of diamond flowers 
a large sapphire ; and a stomacher and necklace, with a 
wreath of- brilliants and sapphire centres, were all scrupu- 
lously matched, and attracted the attention of thousands jfrf 
spectators while the exhibition lasted. 

The Russian jewellers, Messrs. Jahn & Bolin, of St. Pe- 
tersburgh, exhibited a sparkling diadem, containing 11 
v6ry beautiful opals, 67 rubies, 1811 brilliants, and 1712 
roses. A bracelet of turquoises and diamonds, and a 
brooch in the shape of a knob, composed of 750 turquoises, 
with a pair of ear-rings of small turquoises, 709 in number. 

The English jewellers, Messrs. Hunt and Roskell, ex- 
hibit'ed such a profusion of gems, valued at about two hun- 
dred and fifty thousand pounds sterling, that it would re- 
quire a lengthy description to give but a faint idea of them 
• — from the rough diamonds of all sizes, by the hundreds, 
to the most exquisite cut and polished gems. A bouquet 
of diamonds, which was as rich as it was elegant, was made 
so as to be entirely taken to pieces, even to the petals of 



DIAMOND. 213 

the flowers, for the purpose of cleanhig, and for forming 
mto seven l)roaches. They had some particularly beautiful 
bracelets : one in emeralds and diamonds ; another in opal 
and emerald, with white enamel. 

Messrs. R. & S. Garrard & Co., of London, made a sim- 
ilar exhibition of gems and pearls, with a profusion of bril- 
liants and rubies, which would occupy a full page to 
describe. . * 

In the collection of Mr. Herz, in London, both in the 
London Exhibition — exhibited by Mr. Thistlethwayte — as 
well as in his private residence, I examined a very costly 
and unique collection of gems. The diamonds he possesses 
are of every shade and color, such as J have only seen in 
the celebrated Wernerian cabinet at Freiberg, and Abbe 
Hatiy's, at the Jardin des Plantes, in Paris, where they 
were in their natural state, while those of Mr. Herz are 
cut, and many of them set. He had a bouquet of brilliants 
and rubies, valued at four thousand five hundred pounds 
sterling, quite magnificently set; a bracelet of splendid 
Avhite and large diamonds, and in the centre a yellow bril- 
liant of five carats weight, which he valued at five thousand 
pounds sterling. 

Messrs. Blogg & Martin, the diamond brokers of Lon- 
don, kindly opened their treasures to me, and my eyes 
were dazzled by three bags, weighing about five pounds 
each, of diamonds ; most of them cut in the East Indies, and 
weighing from ten to twenty carats. each. They were not 
put in market, but kept as reserve, and the value of that lot 
could not have been less than half a million pounds sterling. 
I beheld many unique curiosities in hemitrope crystals and 
made diamonds ; many thousand carats of rough crys- 
tals of diamonds, from one grain to twenty carats, all as- 
sorted in packages, besides the immense valuable supply of 
perfect rubies of ten carats and upward. The scarcity of 



214 A POPULAR TREATISE ON GEMS. 

these gems in general, and the high price at which the ru- 
bies were then sold in market, formed a very singular con- 
trast while viewino- so lars^e a stock in one establishment. 
I only recollect from memory what I saw in 1851, at 
Messrs. Blogg & Martin's ; the sight of so many valuable 
gems had, however, made a lasting impression on me. 

CORUNDUM. 

The above name was applied to a different species from 
that of sapphire, but these terms are now generally ac- 
knowledged to be synonymous ; not so, however, the ein- 
ery, which does not belong to this species. 

Both occur in rhomboids ; often, too, in cr}:stals of sec- 
ondary form. They scratch all other gems except the dia- 
mond; their streak and powder are w^hite, and the specific 
gravity is 3 '9-4 ; they acquire electricity by rubbing, which 
is .retained for several hours; they are not fusible before 
the blowpipe ; Avith difficulty, by means of borax, they form 
a clear, limpid glass ; acids have no effect on them ; their 
chemical constituents are alumine, silica, and oxide of iron. 

SAPPHIRE. 

This name is derived probably from the Hebrew, as it is 
often mentioned in the Bible. It is not certain whether 
the ancients were acquainted with the blue variety only 
of this gem, and were ignorant of other blue stones, such 
as iazulite, fluor spar, &c. It was not used by them as a 
gem, probably on account of the difficulty of working it ; 
but as a medicine, many peculiar virtues were ascribed to 
it. This species has hitherto been usually divided accord- 
ing to its different colors. The name of ruby has reference 
to a red color, and was applied by the ancients to the car- 



SAPPHIEE. 215 

biincle. SappliirG occurs in crystals, in rounded grains, 
and pebbles. Jt is generally transparent, but sometimes 
only translucent, or displays a shine of light of six rays, re- 
sembling the form of a star. It possesses double refraction 
in a slight degree, and a vivid vitreous lustre, which some- 
times turns to that of mother of pearl. Its fracture is from 
conchoidal to uneven. Its principal colors are blue and 
red, with their various shadings ; sometimes white, gray, 
yellow, green, brownish-green, and black. 

If the red sapphire (ruby) is exposed to a great heat, it 
becomes green, but when cold, returns to its original color ; 
the green sapphire undergoes no changes. 

The various names given to sa|3phire, according to its 
color, are — 

1st. Ruby (Oriental ruby), of a darl^ crimson red, cochi- 
neal or carmine, and rose-red, mostly inclining to violet- 
blue. 

a. Oriental hyacinth, aurora-red. 

2d. Oriental amethyst, palish violet-blue ; playing some- 
times in rose and purple red, like the common amethyst, 
except in its superior lustre. 

3d. White sapphire, limpid aiid perfectly transparent; 
vivid lustre, resembling the diamond. 

4th. Sapphire, Oriental sapphire, from ih^ darkest to the 
lightest blue, with different shadings, whence it is denom- 
inated by different terms, such as male sapphire^ of a per- 
fectly clear Berlin or smalts blue ; female sapphire^ full 
blue, with a tinge of white^ — sometimes sky-blue, with 
streaks or specks; water sapphire^ very pale-blue, and 
sometimes discolored-; cat sapphire^ blackish or greenish 
blue, often not transparent. 

5th. Oriental topaz; lightly yellow, lemon, or brownish 
straw yellow, sometimes playing into green ; it is distin- 
guished from the common or true topaz by color and lus- 



216 A POPULAR TREATISE ON GEMS. 

tre, but it occurs likewise much larger, and is seldom less 
free from faults than any other species of sa-pphire. 

6th. Oriental aquamarine ; greenish blue, pure and 
transparent, possessing a higher lustre and greater hard- 
ness than the common aquamarine. 

Vth. Oriental chrysolite, or peridote.; yellowish-green, 
resembling in color the chrysoberyl, but may be distin- 
guished from it by its higher lustre. 

8th. Oriental emerald ; green, more or less dark, inclin- 
ing to yellow ; it does not equal in color the real emerald, 
but possesses a higher lustre, and is at the same time very 
rare. 

The sapphires which sometimes display a peculiar play 
of light are divided into — 

1st. Star sapphire (asteria, opalescent, or chatoyant sap- 
phire). Some translucent sapphires display, if held before 
the sun, or a burning taper, a white light running in six 
rays, resembling three white planes, or stripes crossing 
themselves at one point. This property is thus visible 
when the sapphire is cut convex (or cabochon), and when 
the principal axis of the crystal stands perpendicular to the 
base of the convex cut stone ; these star sapphires are either 
called ruby-asteria, sapphire-asteria, or topaz-asteria, ac- 
cording to the color they bear. 

2d. Girasol sapphire, Oriental girasol, sunstone sapphire, 
or ruby cat's-eye, have a yellowish, reddish, or bluish shine, 
or reflection of light, generally of a lighter color than the 
stone itself, disj^layed when moved or turned on the convex 
surface. 

Sa23phire is composed of pure alumina ; the opaque con- 
tains about one per cent, oxide of iron and one per cent, 
silica ; before the blowpipe it is unaltered ; fuses with bo- 
rax and salt of phosphorus, but is not attacked by the 
strongest mineral acids ; friction excites electricity, and in 



SAPPHIRE. . 217 

the polished specimens the electrical attraction continues 
for a considerable length of time. The perfect and color- 
less sapphire has a brilliant lustre, so that the same may be 
confounded with the diamond ; its hardness is inferior to 
the latter. The specific gravity of the blue sapphire is 
3'979; of theruby, 3"909; of the green (Oriental emerald), 
3-949; of the violet (amethyst), 3-921. 

The sapphire was well known to the ancients. Pliny 
^ave a description of the star sapphire, under the name 
of asteria. The sapphire possesses the double refraction 
in an iiidiiferent degree, and its fracture is unequal and 
conchoidal. The finest ruby sapphire occurs in the Ca- 
pelan mountains, near Syrian, a city of Pegu, in the 
kingdom of Ava; also in the sand of the Expaillie river, 
in Auvergne. Blue sapphires are brought from Ceylon. 
Large masses of blue sapphire, of opaque color, have been 
found in North Carolina, as well as some isolated crystals 
in Buncombe County, North Carolina ; but there are many 
more localities in the United States, such as New Jersey, 
New York, and Connecticut. Sapphires are mostly found 
in the sands of rivers, or in boulders, with garnets, zircons, 
kyanite, and in basalt. It. has been observed that the blue 
sapphires are frequent in Ceylon, but not the rubies, and 
that in Pegu it is the reverse. The most celebrated mines 
of sapphire are at Mo-gaot and Kyat-Pyan, five days' jour- 
ney from Ava. The Boa, or Emperor of the Birmans, re- 
tains all the larger sapphires. 

For cutting a sapphire an iron mill is used, and for pol- 
ishing, a copper .mill, or one made of alloy of lead and tin, 
to which a horizontal motion is given by a very simple ma- 
chinery ; its surface is charged with diamond powder and 
oil, or with fine emery and water. A thick peg or gauge 
of wood, pierced with small holes in all directions, is set 
upright on the lapidary's bench, close to the mill. The 

10 



218 .A POPULAR TREATISE ON GEMS, 

stone, being placed on the surface of the mill, and the op- 
posite end of the stick to which it is cemented being in- 
serted in one of the holes .of the gauge, the mill is put in 
motion by turning a winch, and the stone kept steady- 
on it. 

When the stone has all the facets, the cutting mill is 
taken out and replaced by one of brass, on which the pol- 
ishing is performed by means of line emery and rotten- 
stone, in the same manner as before. A good judgment is- 
required in determining the form and proportions best 
adapted to set oiF any particular stone to the best advan- 
tage. If the color is full and rich, its transparency perfect, 
and its refractive power considerable, the best form to give 
it is the brilliant. If, on the contrary, the color is dilute, 
the most advantageous method of cutting it is, to cut the 
table side (pavilion) bi'illiant fashion, and the collet side 
(culasse) in steps ; by this means the table itself will be left 
dark, while all the light reflected from the steps on the 
under side of the stone wull be thrown up into the facets, 
by which the table is surrounded. The French lapidaries 
cut the most perfect sapphires in a square or octagon form, 
with a single delicate step between the table and the 
girdle, and three or four steps between the girdle and the 
collet. 

If the sapphires possess a varying chatoyant lustre, or 
are of a small size, their form is always hemispherical or 
elliptical, without any flat facets; the flatter the ellipse 
the more the varying lustre is diffused over the surface of 
the stone ; whereas with a high elli^jse it is condensed on a 
single spot. 

In setting sapphires we always use foil answ^ering to their 
color. The ruby is set with a reddish gold foil, or a foil 
of copper or red glass ; the blue sapphire with a silver foil, 
or blue-colored foil, or with feathers of blue ducks, pigeons, 



SAPPHIRE. 219 

or peacocks ; and the water sapphire in a black back : but 
all perfectly pure sapphires are set d jour. 

Many sapphires may be deprived of their specks by a 
careful calcination in a crucible filled with ashes or clay, 
and they assume then a more agreeable and purer color 
and greater transparency. 

Sapphires are very favorite gems, and are extensively 
used by jewellers for setting in pins, rings, &g. In China, 
the ladies' slippers are mounted with rubies. 

The blue sapphires have of late been employed as lenses 
for microscopes with great success. According to Brews- 
ter, it'is, for its refracting power, second only to the, dia- 
mond, and superior to all other gems. A new use has 
lately been made of the sapphire for drawing wires — it 
being cut in the form of a wedge, through which, by means 
of a diamond-point, a circular hole is drilled and then fast- 
ened on a brass plate ; the wire is drawn through the 
smaller aperture of the sapphire towards the wider, by 
which process it is reduced to a thinness never otherwise 
attained. 

The price of sapphires is very relative, but their propor- 
tional value is next to that of the diamond. The Oriental 
ruby stands highest in value, and w-hen perfect, and ex- 
ceeding three carats, is generally as dear as a diamond of 
equal weight and quality. After the ruby, blue sapphire 
stands next in value ; and as this is not so rare, and occurs 
in large specimens, it is not so high in price. Some put 
the price of the blue sapphire equal to that of the colored 
diamonds ; others put the price at half that of a brilliant 
under similar circumstances. Sometimes the value is fixed 
by multiplying half the price of a sapphire weighing a carat, 
with the square of its weight. It is therefore very difficult 
to come at an exact price-current, and the following aver- 
age prices come nearest to their commercial value : 



220 A POPULAR TREATISE ON GEMS. 



RtlBY. 

Of 1 grain weight 2 francs. 

2 " " 5 " 

3 " " 12 " 

1 carat " 20 " 

2 " " 60 " 

3 " " 150 ." 

4 " " 250 " 

5 " " . 350 " 

BLUE SAPPHIRE. 

1 carat 10 francs. 

2 " 20 " 

3 " 30 *i 

4 " 45 " 

5 " 60 " 

6 " 80 « 

8 " 100 " 

10 " 200 " 

Smaller stones 8 to 1-carat are worth 8 " 

" 12tol " " 6 " 

" 16 to 24 to 1 " " 4 " 

In order to show the various prices of rubies, we cite 
the sale at auction of the Marquis cle Dree's collection, at 
Paris 

For a cherry-red Euby of 2 carats, 1000 francs. 

For a darker Ruby of li " 400 " 

For a bluish-red Euby 2h " 1400 " 

For a lighter Ruby 3 " 120O '* 

For a blue Sapphire 6 " 1760 " 

For an indigo-blue Sapphire 6f " 1500 " 

For a light-blue Sapphire 4 " 123 " 

For a white Sapphire 4i " 400 *' 

For an Oriental Amethyst li " 400 " 

For a fine yellow Topaz 6f " 620 " 

For a lighter Topaz 6? " 71 " 

There are numerous faults and defects to which sapphires 
are subject, and which always influence their price, such as 
clouds, milky or semi-transparent specks, like chalcedony, 



SAPPHIRE. 221 

white stripes, fissures or knots, &g. The sapphire, partic- 
ularly the red and blue varieties, being great favorites in 
commerce, are often imitated, not only by means of other 
colored gems resembling them, but also by substituting 
pastes. Instead of ruby, we sometimes get the spinelle, 
garnet, hyacinth, red quartz, calcined amethyst, red-burnt 
Brazilian topaz, red tourmaline ; and instead of the blue 
sapphire, we get the disthene, kyanite, and the cordier- 
ite, — hardness is the best test. __ 

NOTICE OP SOME LARGE SAPPHIRES. 

Tavernier describes two large rubies said to have be- 
longed to the King of Yisapur, one of Which weighed fifty 
and three quarters carats, and the other seventeen and a half 
carats. The first was valued at sixty thousand francs, 
the other at seventy-four thousand five hundred and thirty 
francs. 

The prettiest sapphire at present in the Impei*ial Museum 
of France, in Paris, is without fault or defect ; it weighs 
132 Y^g carats, and is estimated at 100,000 francs. This 
sapphire was found in Bengal by a poor man who dealt in 
wooden spoons. It belonged afterwards to the mercantile 
house of Rospoli, in Rome, who sold it to a German prince ; 
he again sold it to the jeweller Ferret, of Faris, for 170,000 
francs. 

Two great sapphires belonging to Miss Burdett Coutts, 
of London, and valued at 750,000 francs, were much ad- 
mired at the Faris exhibition in 1855. 

The crown-jewels of France contain about 150 sapphires, 
of an aggregate weight of 350 carats, and are valued at 
600,000 francs. 

Several sapphires with engravings are seen in Rome, 
Buch as Hercules ; in Turin, in the collection of Genevasio, 



222 A POPULAR TREATISE ON GEMS. 

of a Tiberius' head, on white sapphire ; in St. Petersburg, 
and in the French rnnseura. 

Wahls quotes a ruby of 436 carats; and Furetiere saw a 
ruby in Paris of 240 carats; and Tavernier quotes a ruby 
of half the size of an egg, with the engraving of Scheik 
Sepliy. 

The King' of Aracan possesses a crystal of bine sapphire 
of an inch in diameter ; and Sir Abrain Hume possesses a 
distinct crystal of three inches in length. 

The star sapphire on the frontispiece, was formerly in the 
cabinet of Mr. Gilmore in Baltimore. 

The large blue sapphire in Hunt & Roskell's case at 
the London Exhibition, was extremely beautiful, and the 
largest I ever saw. • 

The ruby-sapphire of the East India Company, in Lon- 
don, is certainly the largest in the world. 

Li the collection of Messrs. R. & S. Garrard & Co., in 
the London Exhibition, rubies were in great profusion — 
mostly set with brilliants and pearls. 

The price of rubies, depends upon fineness and color ; 
they are sold in the United States at from three to twenty 
dollars per carat. 

A fine ruby is worth about the same price as a one carat 
diamond ; and a two carat stone, if perfect, is worth more 
than a two carat diamond. 

The King of Pegu and the monarchs of Siam monopo- 
lize the fine rubies, as the sovereigns of the peninsula of 
India have done the diamonds. 

The finest ruby in the world is in the possession of the 
first ; its purity has passed into a proverb, and its worth, 
when compared with gold, is inestimable. 

The Subah of the Deccan is also in possession of a pro- 
digiously fine one, a full inch in diameter. 

The Empress Catharine, of Russia, possessed one ruby 



COEUNDUM. 223 

of the size of a pigeon's egg, presented to her by Gustave 
III., king of Sweden, in 1777. 

Bhie sapphires are described by the English embassy to 
Ava, of the weight of nine hnndred and fifty- one carats. 
Mr. Mawe saw a bhie sapphire of three hundred and ten 
carats. In the crown-jewels of France, there is one i"honi- 
boidal crystal of one hundred and sixty-six carats. 

A beautiful ruby-asteria, in a breastpin, is worn by Mr. 
W. J. Lane, of New York. 

COMMOTS" CORUNDUM, DIAMOND SPAE. 

This mineral was fornierly brought from China only, 
when not so well known as at present, and bore the name 
of common corundum, but it is now considered as belong- 
ing to the general family of corundum. It occurs in crys- 
tals, which are generally coated with some crust ; it has a 
conchoidal fracture, is translucent, and has a lustre between 
unctuous and mother of pearl, either gray, red, blue, green, 
brown, or whitish in different shadings. It is mostly in- 
closed in granite, mica slate, dolomite, or magnetic iron, 
and is found in Piedmont, Cananore, Campo Longo, the 
East Indies, and Sweden. 

All the corundums, possessing fine and pure colors, are 
used and cut as jewels, and the impure pieces are pulver- 
ized and used for cutting and polishing harder stones, or 
glass and metals, particularly so in the East Indies and 
China, and it is called, in Madras, the grinding-spar. 
" It may be remarked that the Chinese corundum, which 
is crystallized in prisms of six sides, bears much resem- 
blance* to the emerald; the hardness and infusibility of 
both these minerals, and their geological position in the 
middle of old rocks increases their similarity; ]?ut the 
emerald cleaves in one direction parallel to its base, while 



224 A POPULAR TREATISE ON GEMS. 

the corundum cleaves in three directions of its primitive 
angles ; the emerald has a less specific gravity, as three to 
four ; the phosphate of lime and the tourmaline are also 
found in six-sided prisms ; but in all these cases are the 
cleavage, hardness, and specific gravity the distinguishing 
characters. The transparent colorless corundum may be 
confounded with the diamond, topaz, aquamarine, white 
spinelle, and quartz ; in these cases the specific gravity is 
the principal distinguishing character ; the white corundum 
weighs 3"970, the diamond 3"o20, aquamarine 2*7, spinelle 
3*64, the topaz 3*4, and the quartz 2'654. 

The emery or granular corundum is of an ash-gray, 
bluish-gray, and sometimes brown color ; is massive, and 
opaque or slightly translucent on the edges ; is very hard, 
and scratches easily glass and quartz ; is found in a bed of 
talc, in mica slate, in rounded masses, in Naxos, Italy, and 
Spain, and in great abundance on the summit of Gunnech- 
dagh, near Gumeschkeny, about twelve miles to the east 
of Ephesus, and between Eskihissar and Males, in Asia 
Minor, and in Ochsenkop, near Schwarzenberg, in Saxony. 
It has been elaborately described by Professor J. Law- 
rence Smith, of Louisville, Ky., as to its power as a polish- 
ing material. He has ascertained that they all contain 
more or less water, and that their specific gravity as well 
as their hardness depends upon the percentage of water 
therein contained ; but the specific gravity of a sapphire, 
ruby, or emerald, which contains no water, is 4'06 to 4'08, 
and that they generally contain from 1*60 to 3*90 per cent. 
of water. This difference does not result from a decom- ' 
position of the mineral but from their formation ; he proves 
that the presence of water in these minerals which influ- 
ences their hardness or specific gravity, was existing while 
they were on the point of crystallization, and his experi- 
ments with the emery from China and Asia Minor, have 



CHETSOBEEYL. 



225 



led him to a scale of hardness to be used in the application 
of emery in polishing the surfaces of certain substances, 
— such as a slab of stone, or a plate of glass, or any 
other material upon which emery is generally applied for 
polishing. Professor Smith's process consists in the fol- 
lowing method : he reduces the emery to a fine powder 
in a steel mortar, similar to the one the diamond-grinders 
use ; the powder is sifted very fine through a sieve. One 
gramme of this fine powder he employs upon a glass plate 
of 0"10 inch diameter, and by means of an agate pestle 
he rubs the powder circularly and rapidly, until the pow- 
der meets with no resistance and makes no scratching 
noise ; the quantity of glass-powder w^hich is hereby taken 
up by the emery gives the index, or the power, of the em- 
erv under trial. 




CHEYSOBEETL, CYMOPHANE. 

The name of this gem is derived from the Greek, and is 
expressive of its color ; it is also called cymophane. It 
was formerly classed with the beryl family, but was sepa- 
rated from that by Werner. 

It occurs, crystallized, in a prismatic form, 
also in boulders and grains ; is transparent 
to translucent, and possesses double refrac- 
tion in a high degree ; its lustre is between 
unctuous and vitreous ; exhibits trichroism ; 
fracture conchoidal; its color asparagus 
and olive green, with a tinge of brown, 
yellow, gray, or white. Some specimens 
display, sometimes, a milky or bluish-white 
lustre. Chrysoberyl scratches topaz and 
rock-crystal very distinctly, but is attacked by sapphire ; 
the streak-powder is white, specific gravity, 3"6-8=^3''75 ; 

10» 



: I 
1 ! 




Fig. 4. 



226 A POPULAR TREATISE ON GEMS. 

liardness, 8 '5. It becomes electric by rubbing, and re- 
tains this i^roperty for several hours : it is infusible by itself 
before the blowpipe, but is slowly fusible into a glass bead 
Avith borax. Its component parts are alumina, silica, and 
glucia, with some oxide of iron and titanium. In com- 
merce, chrysoberyl is called Oriental chrysolite, and that 
displaying lustre is called opalescent chrysolite. Mr. Ebel- 
man has produced, artificially, the chrysoberyl from its in- 
gredients. 

Chrysoberyl is mostly found in loose crystals or in 
boulders in the sand of rivers associated with other gems, 
such as spinelle, sapphire, topaz, beryl, &c. In Brazil, 
particularly in the diamond district, and more frequently 
in Termo Minas Novas, Pegu, Ceylon, and Siberia: like- 
wise in Connecticut (at Haddam), and in New York (at 
Saratoga), imbedded in coarse granular granite, and ac- 
companied by garnet and beryl. 

The chrysoberyl is cut on a brass w^heel w^ith emery, and 
polished on a pewter wheel wdth rotten-stone ; it is very 
often cut in cabochon and, if perfectly pure and transpar- 
ent, in other respects, is set with gold foil, and used for rings 
and pins. 

The chrysoberyl is in no great estimation, on account of 
its indifferent fire and color, but those specimens that take 
a high polish, and occur transparent and pure in color, and 
of varying lustre, are of some value ; it is particularly worn 
in Brazil. At Paris a chrysoberyl of fine green color, oval 
cut, seven lines in length, and five and three quarters in 
breadth, was sold for six hundred francs ; and a very fine 
opalescent chrysoberyl nearly five lines long and four broad, 
cost six hundred and three francs. 

For chrysoberyl have been substituted apatite, fluor spar, 
and pastes ; but it is harder than any of these substances. 
Chrysolite bears a great resemblance to chrysoberyl in its 



SPIXELLE. 227 

external appearance, but is much lighter and softer. A 
green chrysoberyl was found in Termo Minas Novas, which 
w^eighed sixteen pounds, the largest known. It is in the 
possession of the government at Rio de Janeiro. 

SPINELLE. 

This gem was called by the ancients, carbuncle. It only 
occurs crystallized, and mostly in the form of an octahe- 
dron, and its modifications.' The crystals are smooth, 
solitary, or grown together as hemitropes, loose, often 
rounded like grains (figure 5 is 
a made form of the spinelle ruby) ; // \\ 

its fracture is conchoidal ; it is / lJx. n. 

transparent and translucent ; it \<\ ^^^^ >v 
possesses simple refraction of light ; /; Jx 'V-~^ 

is of a highly vitreous lustre ; and U I — ^^ ^^T/^ 

its color is red, turning into the - nA ''^ //K 

greatest variety of shadinofs of / " 3- IHS^ 

blue, brown, and yellow. We t-^^^^^^ 
find, likewise, blue, black, and ^°' 

green spinelles, which, however, have no commercial value, 
on account of their impure color and want of transpa- 
rency. 

Spinelle scratches quartz, and is attacked by sapphire ; 
becomes electric by rubbing; its specific gravity =3*523, 
hardness = 7 "5 6 ; is infusible before the blowpipe. Accord- 
ing to Berzelius, the spinelle of Ceylon w^hen heated, grows 
first brow^n, then black, and then opaque, which, on cooling, 
passes into green and limpid, and ultimately into its origi- 
nal red. Acids do not afiect it ; its component parts are 
magnesia and alumina. The spinelle is classed by jewellers 
and lapidaries according to its various colors. 

1. Ruby spinelle, or spinelle ruby; of a light or dark 



228 A POPULAE TEEATISE ON GEMS. 

red, and no milky lustre ; shows, if held, near the eye, a 
tinge of rose-red color. 

2. Ruby balais, or balais ruby; pale-red or rose-red, 
sometimes with a tinge of brown or violet. 

3. Almandine ruby ; of a cochineal-red color, bordering 
on blue, violet-blue, and reddish-brown. It is distinguished 
frora the garnet, likewise called the almandine, by its lighter 
color, stronger lustre, and greater hardness. 

5. Goiitte de Sang is a fine cochineal- or blood-red spinelle. 

Spinelle is found in clay, and in the sand of rivers, with 
sapphire, garnet, tourmaline, and other gems. The red 
variety occurs in isolated crystals and grains, in alluvial 
soil, and in the sand of rivers — Ceylon, Ava, and Mysore — 
also imbedded in gneiss and granite, in Ceylon; the blue 
varieties occur imbedded in granular limestone at Aker in 
Sweden, Rohleta and Lojusoken in Finland, Straskau Mo- 
ravia, in the dolomite of Nalande, and Candi in Ceylon ; 
the white variety is found at La Ricia, near Rome, with 
black garnet and green augite ; the grass-green variety 
(chlorospinelle) is found in the chlorite slate of Slatoust, in 
the Ural. The black and brown varieties have numerous 
localities ; those from Orange county, New York, are very 
large and perfect octahedrons : one in my possession was 
twelve inches in diameter. Spinelle is cut on an iron or 
brass wheel, with emery or pulverized diamond, and is 
polished either on the same or on a copper wheel, with oil 
of vitriol. 

Spinelle is cut in the same form as the diamond, and is 
set with a foil of copper or gold. Its color is often made 
more intense, and its faults, such as flaws and specks, re- 
moved, by calcining it carefully. 

Lustre, color, and hardness have made the spinelle a 
very favorite gem, which is used in a great yariety of 
ways, as in rings, pins, necklaces, &c. 



TOPAZ. 229 

The price of spinelles it is difficult to determine with 
accuracy, as much depends on their properties ; if perfect 
and exceeding four carats, they are usually worth half the 
price of diamonds equally large. The spinelle ruby and 
balais ruby are the most esteemed spinelles,- and if of 
twenty-four to thirty carats, are worth from two hundred 
to four hundred francs ; and such gems are often sold for 
true rubies (sapphire). 

Zircon is of greater specific gravity and less hardness 
than the spinelle, and shows strong and double refraction 
of light. Calcined topaz is distinguished by its ^ electric 
properties. Burnt amethysts are lighter, and are scratched 
by spinelle. Pastes are likewise substituted for the 'spinelle, 
such as glass colored with gold-purple ; but as the spinelles 
are always harder and heavier, the adulterations may soon 
be detected. 

According to Mr. Ebelman, the artificial spinelle is ob- 
tained by the following mixture, which is put into a platina 
capsule and exposed to the heat of a porcelain furnace : 
Alum, - - - , . 6 grains. 
Magnesia, . - _ 3 " 

Fused boracic acid, - - 6 " 
Oxide chrome, - - * O'lO to 0-15. 

TOPAZ. 

It is not determined whether the ancients meant by 
topaz the same gem as we describe, since the Greeks un- 
derstood the topaz to bs of a transparent gold-yellow, and 
the Romans, of a transparent green- yellow. The name, 
which, according to Pliny, is derived from Topazos, an 
island in the Red Sea, has no reference to its color. To- 
paz was, in former times, thought to possess great medicinal 
virtues; for example, as a remedy for mania, and as a 



230 



A POPULAR TREATISE ON GEMS. 





Fig. 6. 



Strengthening medicine. The topaz occurs crystallized in 
a rhombic prism, but mostly in very complicated forms, 
particularly the Brazilian, Siberian, and 
Saxonian : it is often found in boulders. 
Its fracture is conchoidal ; it is transpa- 
rent and translucent ; possesses some 
double refracting powers ; a very vivid 
vitreous lustre ; clear, straw, sulphur, 
wine, and gold yellow colors, sometimes 
with a tinge of violet-blue, greenish, and 
white. ^ Topaz scratches quartz distinctly, 
but is attacked by sapphire. Its streak- 
powder is white ; specific gravity, 3*49 to 
3'56 ; it is phosphorescent when heated, 
with a bluish or yellowish lustre, in small fragments. It 
becomes electric either by rubbing, heating, or by pressure, 
and retains the property for more than twenty-four hours. 
Before the blowpipe, at a strong heat, it is covered with 
many small bubbles, and partly loses its color. It is dis- 
solved, fusing slowly with borax, into a white bead ; acids 
have no effect upon it. Its component parts are alumina, 
silica, and fluoric acid. 

In commerce, topaz is distinguished by the following 
names : 

1. Water drops, pebbles (gouttes d'eau)^ clear, limpid. 

2. Siberian topaz, white, with a bluish tinge. 

3. Brazilian topaz, gold-yellow, with a touch of red. 

4. Saxon topaz, pale wine-yellow. 

5. Indian topaz, saffi'on-yellow. 

6. Brazilian ruby, light rose-red. 
1. Brazilian sapphire, light-blue. 

8. Aquamarine^ sea and mountain green. 
Topaz belongs to primitive rocks, and is found in chlorite 
slate, gneiss on gangues, argillaceous schist, &c. In Bra- 



TOPAZ. 231 

zil, it is found in a decomposing chlorite slate (and is there 
called malacheta), within brown hematite cavities or quartz 
gangues, winch are of one inch to one and a half feet thick, 
and are overlaid by indm-ated talc and white and brown 
kaolin, and sometimes intermixed with quartz crystals 
and micaceous iron, which are the surest indications of 
topaz. Such topaz localities are at Villa Rica, Capao, and 
Lana. Little attention is paid during the dry season to 
the (jigging of topaz ; but with the beginning of the rainy 
season, the searches for topaz are undertaken, and the 
operation for w^ashing and procuring them is performed 
like that of the diamond, mentioned under its proper 
head. 

In places where the topaz is found in company with tin 
ore, it is picked out ; but where it forms a part of the rock, 
it is wrought by mining operations, as in Saxony. 

Topaz is cut on a leaden wheel, either with emery or pul- 
verized topaz, and is polished on a copper wheel with rotten- 
stone. Care has to be taken in slitting the foliage. The 
forms which it is to receive depend upon its qualities and 
purposes. The white topaz is cut in brilliant form, with a 
small table ; the bluish topaz, however, is cut with a mixed 
form, but it is to be observed that the table side requires 
to be higher than usual, the table smaller, and the collet 
side, with its steps, must be attentively wrought in propor- 
tional distance. The yellow topaz is mostly cut as brilliant 
or table-stone, and in setting, its back is supplied with a 
gold foil, and the pale with a red-colored foil. Many spe- 
cies of topaz are set d jour. Topaz assumes, by calcining, 
a different color, and also by coloring fluids, as stated in a 
former chapter. 

The topaz is in general use by jewellers for setting in 
rings, pins, ear-rings, seals, or necklaces. Its fragments 
are pulverized and used for grinding the softer precious 



232 A Popular treatise on gems. 

stones ; this is effected by calcining them first, then throw- 
ing them into water, and afterwards 'pulverizing them. 

By heat the topaz assumes a pink or red hue, so nearly 
resembling the balais ruby that it can only be distinguished 
by the facility with which it becomes electric by friction. 

Topazes from New South Wales, Brazil, and Scotland, 
sometimes contain cavities, in which Sir David Brewster 
discovered two fluids, one of which has an index of refrac- 
tion =1*2 11, and expands 0*25 of its original volunje on 
being heated, from 10° to 27°. 

The topaz is found green, blue, and colorless at Ala- 
baschkka Meersinsck, Miask, and Adum Tschelon in Sibe- 
ria ; Kamtschatka, Peru, and Rozena in Moravia, with lep- 
idolite ; Mucla in Asia Minor, Peneg in Saxony, and at 
Schneckenstein, near Auerbach, in Saxony, of a wine-yellow 
color; at Villa Rica, in Brazil, of a deep-yellow color; 
with tin ore at Geyer, Ehrenfriedersdorf, and Altenberg 
in Saxony, Schlackenwald in Bohemia; with tin ore and 
apatite in veins of granite at St. Michael's Mount and Huel- 
kind, near St. Agnes in Cornwall ; in granite in the Moi-ne 
mountains in Ireland ; in the United States, at. Trumbull 
and Middletown, Connecticut. 

The less transparent variety (pyrophysalite), with fluor 
in granite veins, at Tinbo, near Fahlun, in Sweden ; in boul- 
ders at Braddbo, in Sweden ; in gneiss at Fossun, in Norway. 

Topaz is generally of less value now than formerly, owing 
to the yearly supplies obtained from Brazil, which is about 
forty pounds. The mine at Capao has yielded aboilt twelve 
thousand dollars' worth, and the supply has been accumu- 
lating at Rio de Janeiro and Bahia to such a degree, that 
it is disposed of at a less price there than at the mines. 

Those most esteemed are the rose-red and the white, or 
water drops, pingos cTagoa. A topaz of the size of a bean 
is sold at Chapada, in the Termo Minas Novas, at one 



TOPAZ. . -233 

dollar ; one of one carat is disposed of at an average rate, 
for eight dollars; a yellow one for tliree dollars; and a 
yellow burnt one for five dollars. In Brazil, very large, 
fine, and lustrous ones, bring thirty dollars. 

The Saxonian topazes are less valued, yet good yellow 
or crimson colored ones, nine lines long and seven broad, 
bring four hundred and twenty francs. 

Aquamarine and chrysolite are sometimes substituted 
for topaz ; but it may easily be distinguished from them, 
not only by its hardness, fracture, and specific gravity, but 
more especially by its property of becoming electric by 
rubbing. This will prevent the substitution of either of 
the above, or those most resembling them; such as the 
yellow quartz, chalcedony, or other yellow-colored stones. 

According to the account pf Tavernier, the Grand Mogul 
possessed an octangular polished topaz of one hundred and 
fifty-seven and three quarters carats weight, which has been 
purchased for sixty thousand dollars. 

M. d'Eshwege notices a topaz crystal ten inches in length 
and four inches in diameter. The United States (Connect- 
icut) yield topazes of an opaque color, pale, dark orange, 
and yellow, twelve inches in length. One of the finest 
Brazilian topazes I have seen is in the rare collection of 
Robert Gilmore, Esq., of three inches length, and perfectly 
terminated. The Brazilian topaz on the frontispiece was 
exhibited in the London Palace by Mr. Tennant. Some 
very splendid cut Oriental topazes I saw at Mr, Stephen 
H. Palmer's ; they were of wine-yellow color and good size. 

In the French Imperial Bibliotheque there are several 
engraved topazes — Phihp II. and Don Carlos in white 
topaz, and engraved by Jacques de Trezzo ; and in a A^ery 
large and deep yellow topaz, an Indian Bacchus, in the 
Vatican. The House of Orleans had a Mercury seen in 
profile, on an Oriental topaz, with eight facets. 



234 



A POPULAR TREATISE ON GEMS. 



In Turin, in the Generosio collection, was a topaz in- 
taglio, representing Victory in a chariot drawn by two 
horses. 

Caire possessed an OrientTil topaz of twenty-nine carats, 
pierced lengthwise, with the fqllowing words in Arabic let- 
ters : " God only will accomplish." It was an amulet, 
known by the Arabs as gri-gri. 

The ancient rona^ov was found on an island in the Red 
Sea, which was often surrounded with fog, and therefore 
difficult to find ; it was hence named rona^a, to seek. This 
name, like most of the mineralogical terms of the ancients, 
was applied to several distinct species. Pliny describes a 
statue of Arsinoe, the wife of Ptolemy Philadelphus, four 
cubits high, Avhich was made of rorra^ov^ but evidently not 
the topaz of the present day^ nor chrysolite, which has 
been supposed to be the ancient topaz. It has been con- 
jectured that it was a jasj^er or agate ; others have imagined 
it to be a prase or chrysoprase. 



EUCLASE. 

Monoclinohedric figures ; cleavage clinodiagonal, highly 
j^erfect, very brittle and fragile ; con- 
choidal fracture ; hardness, 7*5 ; spe- 
cific gravity, 3* ; transparent ; splendid 
vitreous pale mountain-green, passing 
into yellow, blue, or white. When 
heated before the blowpipe, it intu- 
mesces, and melts in thin splinters to a 
white enamel; is not acted upon by 
acids; is composed of 44*7 silica, 31"8 
alumina, and 23*5 glucine, with 1 to 
22 peroxide of iron, and 0*4 to 0*7 
oxide of tin. It is found in chlorite 
slate at Boa Vista and Capao, near 




Fig. 7. 



J 



EMERALD. 235 

Villa Rica, in Brazil ; in Peru, and is said to have been 
found in Siberia. It is very rare, and for this reason not 
much used as a gem ; it resembles much the aquamarine 
when cut. 

EMERALD. 

The emerald proper and the beryl belong to. this mineral 
species, and are distinguished by their color and crystalline 
form. The emerald occurs in six-sided prisms with their 
modifications; it scratches quartz, and is scratched by 
topaz. The streak-powder is white ; its hardness is 7'5 to 
8*0 ; specific gravity, 2*73 to 2''76 ; it becomes electric by 
rubbing ; it is rounding before the blowpipe, and forms an 
opaque black, but becomes a green or limpid glass, having 
the hardness of borax. Its constituents are glucia, alumina, 
and silica. 

THE EMERALD PROPER. 

The emerald appears to have been known in the most 
remote ages, and was the third stone, according to Cal- 
met's arrangement, on the high priest's breastplate of judg- 
ment, witli the name of Zebulon inscribed on it. In the 
time of Pliny, this stone was held in such high estimation 
that it was seldom if ever engraved upon. The moderns, 
however, did engrave on the same, as we find in the royal 
collection at Paris a head of Plenry IV., and one of Louis 
XIV. It has been excavated from the ruins of Rome, and 
from Herculaneum and Pompeii. But the ancients often 
included under this name other gems of the same color ; 
such as the green fluor, aquamarine, jasper, malachite, &c. 
They appear to have obtained the emerald from Egypt. 
Caiiloud has in modern times succeeded in finding the old 
emerald mines in the Theban deserts, on the Arabian Gulf 
— which have been noticed by the ancient authors, and by 



236 A POPULAR TEEATISE ON GEMS. 

the traditions of the Arabs, as coming from the mountains 
of the Sahara — when sent on an exploring expedition by 
the Pasha of Egypt. He mentions having found subterra- 
nean mines, capable of allowing four hundred men to work ; 
and he likewise found tools, ropes, lamps, and other uten- 
sils. He judged from the ruins of the architecture of the 
temples of a city which he discovered, that they were of 
Egyptian or Grecian form, and about one thousand years 
old. 

Among the church treasures of the ninth and tenth centu- 
ries, we find the emerald, which came into particular notice 
after the conquest of Peru, where an emerald the size of 
an ostrich egg is said to have been idolatrized by the savage 
inhabitants^ The emerald was formerly used as medicine, 
and was worn as a preventive against epilepsy. 

The. emerald occurs in somewhat depressed 
six-sided prisms ; the lateral faces of which are 
smooth ; the fracture is conchoidal to uneven ; 
it is transparent to translucent ; displays double 
refraction in a slight degree ; has a vitreous 
lustre ; is green and emerald-green with its 
different shades. 

According to Mr. Ebelmatt, the true emerald is pre- 
pared artificially by 

Silica '7* grains. 

Alumina - - - - I'GO " 

-—— ^Glucia 1-40 " 

Fused boracic acid ' - - 4'06 " 

Oxide chrome . - . 0*10 " 

It is scratched by an Enghsh file, and scratches strongly 
white glass, and slightly quartz. Its specific gravity is 2'1S 
to 2-77. Its color is owing to the oxide of chrome. An 
emerald when calcined, and thrown into water, crumbles 



^ 



Fig. 8. 



EMEEALD. 23 V 

into pieces of different colors. The purest emeralds are 
called the Peruvian. 

TJie emerald is found in micaceous schist at Salzburg, in 
the Sahara mountains, in gangues in Peru, in the argilla- 
ceous and in hornblende slate. Formerly, the finest 
emeralds came from Warta, in Peru ; but the mine is 
either exhausted, or the Indians filled up the mines before 
they left them at the conquest. The best are now found 
in the valley of Tunca, in Santa Fe, where they occur in 
granite. The emerald has lately been discovered in Siberia, 
in the micaceous schist, and is equal to the Peruvian in 
every respect. 

The emerald is sawed into pieces with emery, cut on the 
copper wheel, and polished on a finer wheel with rotten- 
stone, pumice-stone, tin-ashes, and water. The step-cut, 
and the mixed step-cut, or the table-cut, are mostly used, 
yet it is sometimes cut as a brilliant or rose-cut. They are 
set with a green foil or green satin on their back ; or some- 
times in a back colored with mastic, and very black ; but 
if perfectly pure, and of fine color, they are set djour. On 
exposure to air, emeralds grow by degrees paler. 

The emerald is, on account of its agreeable green color, 
a very favorite ornament, and is used for the most expen- 
sive kinds of jewelry. Its value dej^ends altogether upon 
its pure and fine color, vivid lustre, and the size of the 
specimen. The price of emeralds was much higher before 
than it has been since the discovery of Mexico ; the prod- 
uct of the mines of Peru reduced their price considerably ; 
now they are getting deai'er again, and always command a 
good price. A small box of fair emeralds from Peru, 
which I saw a few years ago, at the office of the American 
and Foreign Agency, in this city, which weighed from 
three to four pounds, was sold afterwards at Paris for nine 
thousand francs. A good emerald, of fine color, is worth 



238 A POPULAR TREATISE ON GEMS. 

twelve dollars per carat ; and the price increases according 
to its interior qualities. The price of the best emeralds of 

4 grains is - - - 18 dollars, 

8 • " ... 30 " 

16 " ... 200 " 

24 " ... 300 " 

48 " ... 1000 " 

Good emeralds, meaning good color and quite free from 
flaws, are very rare, and have nearly as much value as the 
ruby. 

An emerald of twenty-four grains, and good color, was 
sold at the auction of the Marquis de Dree, for two thou- 
sand four hundred francs. Emeralds of indifferent pale 
color, are sold for two dollars per carat. The faults to 
which emeralds are subject, are inequality of color and 
transparency, dark or white spots, fissures, and feathers. 

For emeralds, there are sometipies substituted the green 
tourmaline and apatite ; the former is easily detected by 
its property of becoming electric by heating ; but in gen- 
eral all these stones do not possess the lustre and hardness 
of the emerald. The pastes in imitation of the emerald, 
are so well manufactured that it is often difficult to dis- 
criminate the genuine fi'om the false. The following yields 
the best imitation of the emerald : 

1000 parts of discolored strass, 
8 " pure oxide of copper, 

•02 " oxide of chrome. 

An emerald is said to have been at the Chapel of our 
Lady at Loretto, in Italy, larger than a man's head, and for 
which an Englishman offered ninety thousand crowns. 

The Sultan of Oude, in the East Indies, is said to have 
given to the King of England, among other presents, an 
emerald of the size of a hen's egg. 



EMEEALD. 239 

The treasury of Vienna is said to contain an emerald of 
two thousand two hundred and five carats, valued at three 
hundred thousand crowns. 

The most magnificent specimen of emerald was presented 
to the cathedral of Loretto,' by one of the Spanish kings. 
It consists of a mass of white quartz, thickly implanted 
with emeralds, more than an inch in diameter. 

An emerald belonging to the crown of Russia, is noticed 
in the Memoir es du rhgne de Catherine, Irnperatrice de 
JRiissie, as being of the size of a hen's ego^. 

A fine crystal in the matrix, is in the museum at Dres- 
den, which I examined in 1827. 

Among the large emeralds stands foremost the magnifi- 
cent crystal belonging to the Duke of Devonshire, as repre- 
sented, on the frontispiece of this work; it is a regular 
six-sided prism, perfectly well formed ; two of the parallel 
faces are more developed than the others, so that the 
hexagonal base of the crystal has one side larger than 
the rest; the dimensions of the base are 2'36 inches, by 
1"97 in diameter, and it weighs eight ounces and eighteen 
pennyweights ; it is of a fine green color and perfectly 
clear in the upper part, it was found in a vein of dolomite, 
which traverses a hornblende rock at Muso, near Santa Fe 
de Bogota, in New Grenada. , 

A prettier but smaller specimen, weighing but six ounces, 
is in the possession of Mr. Hope, of London. 

Mount Zalora, in Upper Egypt, afibrds a less distinct 
variety, and was the only locality which was known to the 
ancients. 

At the New York Exhibition, in 1853, quite a number 
of emeralds were shown from the New Grenada mine. 

Dr. J. K. Chilton, of New York, has a very beautiful 
crystal of emerald in the matrix in his private cabinet, of 
one inch in lenorth. 



240 A POPULAR TREATISE ON GEMS. 

The largest cut emeralds and in great profusion, set in 
bridles, saddles, and in the girdle of an apron, about the 
size of pigeons' eggs, were in the East India Company's 
collection. From forty to fifty of that size were set to- 
gether, some of them not well cut and polished, but all 
transparent and of beautiful green color, they were cer- 
tainly very valuable. 

Mr. Herz, of London, has a beautiful polished emerald 
of 112 carats. 

Mr. Stephen H. Palmer, jeweller of this .city, has some 
very fine cut emeralds, one of which weighs four and seven 
eighths carats, for which he asks $350. 

The prettiest cut emerald is in the imperial cabinet of 
St. Petersburg ; it weighs thirty carats ; is of pure color, 
and a perfect stone ; it has a round form with too- many 
facets. 

■The emerald has been very successfully imitated, so 
much so that the most experienced eye may sometimes be 
deceived. 

BERYL, AQUAMARINE. 

This gem was likewise known to the ancients, who con- 
sidered and described it as a sea-green precious stone, and 
called the yellow varieties of this mineral the chrysoberyl. 
It was used by the Romans as ornaments for cups, also for 
cameos. The crystals of the beryl are six-sided, terminated 
by six-sided pyramids, they also taper gradually from one 
end to the other ; the lateral faces are striated ; the frao- 
ture is conchoidal or uneven ; they are transjDarent or trans- 
lucent at the angles, with indistinct double refraction, and 
vitreous lustre : the colors are green, bluish-green, yellow- 
ish-green, or greenish-white ; bluish, sky, smalts, or indigo 
blue ; straw, wax, or honey yellow ; all pale colors : hard- 
ness,Y'5 ; specific gravity, 2*67 to 2'71. According to its 



BERYL. 241 

color and transparency, it is designated the common and 
precious beryl : imder the first are generally comprised the 
greenish and blue varieties, which are also called the aqua- 
marine; whereas the yellowish varieties are exclusively 
called the beryl, and are generally divided thus : 

1. Aquamarine, pure pale sky-blue. 

2. Siberian aquamarine, pale greenish-yellow, of a vivid 
lustre, faint color. 

3. Aquamarine chrysolite, greenish-yellow, and yellowish- 
green, vivid lustre. 

The beryl belongs to the primitive formation, is found 
in quartz veins and granite (graphic granite), and is associ- 
ated with garnets, quartz, chrysoberyl, schorl, topaz, &c. 
The most magnificent beryls come from Siberia, Rio de 
Janeiro in Brazil, Aberdeenshire in Scotland, and Limoges 
in France. The common and translucent beryl occurs all 
over the globe, and in the United States in great abund- 
ance, where it is without mercantile value. The granite 
rocks of New Hampshire (at Acworth), have brought 
forth gigantic beryls, perfect six-sided crystals, three feet 
in length and four feet in circumference, and weighing up- 
wards of three hundred pounds, and some with a distinct 
termination of the crystals. Specimens of this description 
may be seen in the collection of the Lyceum of Natural 
History, New York, in Mr. Gilmore's collection at Balti- 
more, and in the author's collection. Large quantities of 
beryl crystals have also been found in Chester county, 
Pennsylvania. 

The beryl is cut on a leaden plate with emery, and 
polished with rotten-stone on a tin plate, and generally of 
the brilHant cut, on accoxmt of its not possessing much 
lustre in the interior. 

The foil that is required in mounting, depends upon the 
color of the stone : the greenish variety, for instance, is set 

11 



242 A POPULAR TREATISE ON GEMS. 

with a greenish-bliie foil ; the pale is set in a black ground, 
like the diamond, or on a silvery foil. 

Beryl is employed in jewelry for rings, pins, ear-drops, 
seals, &c. : but on account of its softness it is rendered 
less lasting, and as by wearing it loses all its beauty, it 
does not command a high price in market, being much 
below that of the emerald. 

A beryl of a carat, averages about one dollar and fifty 
cents, and the price increases in the same ratio with the 
number of carats. The beryl is subject to such faults as 
spots, feathers, and fissures. 

For the beryl, is sometimes substituted chrysolite, which 
is softer, however ; it is also imitated by paste, which is 
likewise softer than beryl. , 

One of the largest transparent beryls, weighing five 
hundred and ninety-five carats, was once in the possession 
of a mineralogist at Vienna. In 1811, a beryl of fifteen 
pounds, pure, was discovered in Brazil. In 1825, a beau- 
tiful rounded Brazilian beryl, of four pounds weight, was 
offered for sale for six hundred pounds sterling. 

Ma we describes a pure transparent beryl, altogether free 
of faults, seven inches long and three quarters of an inch 
thick. 

In 1827, a superb aquamarine, weighing thirty-five gram- 
mes, was found in the borough of Mowzzinskaia, in Siberia, 
which the Russians are said to value at six hundred thousand 
francs. A very remarkable aquamarine, of extraordinary 
size, ornamented the tiara of Pope Julius I. . ' 

There is also a very fine aquamarine in the Imperial 
Library of Paris, on which there is a well-executed en- 
graving, by Erodus, of Julia, daughter of Titus. 

There is, according to Caire, another aquamarine in 
London, weighing five hundred and forty carats. In the 
Mineralogical Museum, of Paris, there is an aquamarine 



BERYL. 243 

weighing one hundred and thirty-three grains; and another 
one in a rough state, and extremely beautiful, weighing 
over twenty carats, for which 15,000 francs were offered. 

There are many of the intaglios of the ancients in the 
aquamarine. 

Pliny speaks of the finest beryls as those " qui viridatem 
puri maris imitantur," and hence the term aquamarine is 
applied to those beryls which have beautiful shades of sky- 
blue or mountain-green colors. 

The aquamarine was much employed by the ancients for 
engraving : there is one by Quintillius, of Neptune mounted 
on marine horses ; another of a dranken Hercules, by Hyllus. 

A similar intaglio, with terrestrial instead of sea horses, 
is the treasure of Odescalchi. 

The specimen of beryl on the frontispiece was the prop- 
erty of Baron Struve, Russian ambassador at Hamburgh ; it 
was of grass-green color, fifteen inches long and two inches 
in diameter. A similar, but smaller, specimen, and more 
yellowish-green in color, was in the case of Mr. J. Tennant, 
of London, at the Exhibition of 1851. Both are Siberian 
beryls. The most splendid specimen, weighing eighteen 
and a half pounds, which formerly belonged to Don Pedro, 
in size and form, resembles the head of a calf, and exhibits 
a crystalline structure on one side only ; the rest is water- 
worn, perfectly transparent, ^nd without a flaw, and of 
a fine pale bottle-green color. Beryls are frequently ob- 
tained in Brazil and Siberia of one foot in length, but they 
are commonly very deeply striated longitudinally. 

Mr. Francis Alger, of Boston, informed the author of 
having obtained a huge beryl crystal nearly perfect, of one 
thousand pounds weight, from Acworth, in New Hampshire, 
about fifteen miles from Bellows' Falls. Beryls occur there 
in extensive veins of granite, traversing the gneiss. The 
localities of beryl are very numerous in the United States. 



244 A POPULAR TREATISE ON GEMS. 

In graphic granite, associated with black tourmaline, good 
clear crystals are found in Bocodoniham, and Taphain, 
Georgetown, Parker's Island, and at the mouth of Kene- 
bec river, in the State of Maine ; at Goshen and Chester- 
field, Mass., in irregular crystals of a pale-green color ; and 
transparent, at Monroe, in Conn., in a granite vein ; in 
Haddam, Conn., at the chrysoberyl locality, w^here the 
beryls of yellow and yellowish-green colors are imbedded 
with crystals of chrysoberyl and columbite. 



ZIRCON, HYACINTH, JARGON. 

Zircon and hyacinth were regarded as distinct minerals 
until the improvement in chemical analysis proved the same 
constituents to exist in both, particularly zirconia, a peculiar 
earth: they are now^ considered as two varieties of one and 
the same mineral. Zircon is also called jargon, and this 
name is either of Ceylonese or French origin. The an- 
cients denominated hyacinth, the gem which is now known 
by the name of carbuncle ; their true hyacinth was a dark 
amethyst. The zircon was formerly used as a celebrated 
medicine. 

Zircon crystallizes in four-sided prisms, terminated by 
four-sided pyramids, with various modifications ;* the crys- 
tals are smooth, rough, or ' uneven-j it occurs likewise in 
rounded pebbles; it is transparent and translucent; pos- 
sesses double refraction in a great degree ; and has a vivid 
vitreous lustre, approaching sometimes to adamantine. 
Color, from hyacinth-red to yellow and brown ; also, red, 
gray, white, brown, and greenish-gray. It slightly scratches 



* See in the frontispiece, a beautiful American zircon, from the cabinet 
of Dr. J. R. Chilton, of New York. It was found in Buncombe county, 
North Carolina. 



ziECpN. 245 

quartz, but is attacked by the topaz ; its streak yields a 
white powder ; specific gravity is 4*00 to 4*70 ; hardness, 
7'5 ; it becomes electric by friction ; is infusible before the 
blowpipe, but loses its color at a low heat, the yellowish- 
brown, however, becomes redder; acids do not act upon 
it. Its chemical constituents are zirconia and silica, with 
about two per cent, oxide of iron, which is the coloiing 
principle. 

1st. Zircon, called by jewellers Ceylonian zircon, — fire- 
.red, yellow, yellowish-green, and gray. 

2d. Hyacinth is called by jewellers the Oriental hya- 
cinth, which is of a hyacinth-red, deep red, with a touch of 
the brown, and sometimes orange-yellow color. Zircon 
occurs in primitive rocks, and forms a j^art of the zircon 
sienite of Norway and other countries. It is also found 
in gneiss, granite, amygdaloid, and basalt. It is likewise 
found in the beds of rivers; and there are localities in 
Ceylon, Pegu, Madras, France, Bohemia, Saxony, Italy, 
Siberia, Silesia, Scotland, the Canadas, &c. Very fine crys- 
tals, loose or attached to felspar, are found in Buncombe 
county. North Carolina. 

The zircon is cut with diamond-powder, or emery, on a 
copper wheel, and is polished with rotten-stone on a tin 
plate, and is generally cut in the rose, table, or thick-stone, 
and sometimes the brilliant form. The foil generally used 
in mounting, is that corresponding to its color ; or it is 
mounted in a black ground. If zircon is calcined in a 
crucible filled with lime, it loses its color almost entirely, 
and has then the appearance of a pale straw-yellow dia- 
mond, for which it may also be substituted. It is employed 
in jewelry for rings, breastpins, eai'-rings, or for ornament- 
ing watch-cases and snuft-boxes; also, for jewelling watches 
and for supporting fine balances. The value of zircon de- 
pends j)rincipally u^oon the purity of the color, but the 



246 A POPULAR TREATISE OX GEMS. 

color of hyacinth is preferable to that of zircon ; a carat of 
the former is worth from fifteen to twenty dollars. Zircon 
is imitated by pastes, which may easily be detected by their 
lustre, hardness, and specific gravity ; burnt topaz may be 
substituted for it. 

The jargon is a variety of zircon, being composed of the 
same constituents, and diflfering merely in color fi-om the 
first. It is mostly of white, grayish-white, and greenish- 
white colors, with tinges of green, blue, red, and yellow ; 
but generally of a smoky white color. It usually occurs in 
worn angular pieces, or in small, detached crystals, of an 
octahedral form. The crystals are smooth, and of a bright 
adamantine lustre; have a conchoidal fracture, and double 
refraction ; seldom quite transparent ; is harder than quartz, 
and of a specific gravity of 4*3 ; loses its color when ex- 
posed to the blowpipe flame, but is infusible. It occurs 
chiefly in the sand of a river in Ceylon, accompanied by 
sapphire, spinelle, tourmaline, &c. 

On account of its peculiar adamantine lustre, it has often 
been substituted for the diamond, and a century ago it was 
regarded as an inferior variety of the true diamond, and few 
of the precious stones were in more request, especially for 
mourning ornaments, for which the dark tone of its color, 
combined with its lustre, was supposed peculiarly appro- 
priate. It has no value, at present, in market, although 
it is still seen in the cabinet and in the collections of 
jewellers. 

Hyacinth difiers from jargon and zircon only in color, 
being of a red orange color, very bright and transparent ; 
it is much more employed for setting than zircon. It 
occurs also in the s^nd and alluvial deposits of some rivers 
in Ceylon ; at Espaillie, near Puy, in France ; at Ohlapian, 
in Transylvania ; occasionally in volcanic tufa, in Auvergne, 
and at Vesuvius. Siberia aflbrds crystals as large as wal- 



GARNET. 247 

nuts. Splendid specimens occur also in Greenland and 
Norway. 

Hyacinth is not liiglily j)rized by the jeweller. A 
large hyacinth of two hundred and fifty carats, in the col- 
lection of Mr. Herz, of London, was offered at a nominal 
sum of fifty pounds. Wm. J. Lane, Esq., of 'New York, 
has a beautiful seal-stone of hyacinth, which the author has 
much admired. Mr. Herz has also a cut zircon of forty-six 
carats, which he values very highly. 

It is very doubtful whether the modern hyacinth is one 
of the number of stones called hyacinths, vdfavOog, by the 
ancients. It is supposed that the name was aj)plied to the 
amethyst or sapphire. 

GAEISTET. 

Garnet was well known to the ancients, who consid- 
ered the carbuncle as the same mineral, representing the 
whole species. It has been found among the ruins of Rome, 
in a variety of cut forms. But the name garnet is of 
modern origin, and probably was bestowed on this mineral 
from being found mostly in grains. 

The garnet crystallizes in dodecahedral forms, with many 
modifications; the crystals are sometimes flattened into 
tables ; it is also found in round angular grains, and mas- 
sive ; the structure is imperfectly lamellar ; fracture, more 
or less conchoidal, sometimes uneven and brittle; lustre, 
shining vitreous; it is transparent and translucent; the 
color is blood, cherry, or brownish red, but almost invariably 
with a violet or blue tinge ; sometimes, however, we find 
garnet of a yellow, green, brown, or black color. 

The red garnet scratches quartz faintly, but is attacked 
by topaz, and even by the file ; its powder is reddish-green ; 
hardness, 6*5 to 7*5 ; specific gravity is from 3*10 to 4-30 ; 



248 A POPULAR TREATISE ON GEMS. 

it becomes electric by friction ; heated by itself, the garnet 
grows darker, but resumes its color when cooled ; it fuses 
before the blowpipe into a black pebble. Its chemical 
constituents are silica, alumina, and the protoxides of iron 
and manganese. 

Garnet has names according to the different shadings of 
color : 

1st. Syrian garnet, which is also called the Oriental and 
precious garnet, almandine, carbuncle ; this is of a blood- 
red, dark crimson color. 

2d. Bohemian, or Ceylonese garnet, called the pyrope ; 
wine-red, nearly orange-yellow, deep colored. 

3d. Yeimeille, or Aplome, having a deep shade of orange- 
yellow! 

Pliny describes vessels of the capacity of a pint, formed 
from carbuncles — " non claros ac plerumque sordidos ac sem- 
per fulgoris horridi" — devoid of lustre and beauty of color, 
which probably were large common garnets. The garnet 
is also supposed to have been the hyacinth of the ancients. 

Pyrope is described as presenting a dark blood-red 
color by reflected light, but yellow by transmitted light. 
Pyrope was so called from nvp, fire, OTrro/zai, to see, in allu- 
sion to its color. 

The almandine, or precious garnet, is transparent and 
brownish-red, while pyrope is blood-red. The red gar- 
net occurs imbedded in mica slate, granite, and gneiss, 
rarely in limestone, chlorite slate, serpentine, *and lava, and 
is found in the greatest perfection in Ceylon, in the sand of 
rivers ; and in the alluvial soil of Pegu, Hindostan, Brazil, . 
and Greenland ; in Bohemia, in alluvium, near Collin ; in 
gneiss at Zbislau ; in Tyrol, in the Oetzthal, and on the 
Greiner, in Carinthia, Styria; in Switzerland; at Ariolo, 
Canaria, Maggia ; in Hungary, Sweden, Norway, Scotland, 
Spain ; and in the United States^ in North Carolina, Geor- 



GAENET. 249 

gia, Massachusetts, and Kew Hampshire. Professor Ed- 
ward Hitchcock once exhibited to the author some beautiful 
cut precious garnets from Berkshire county, Massachusetts ; 
the Hon. Mr. Chngman, U. S. Senator from Korth Caro- 
lina, has some very handsome transparent garnets from his 
district in Buncombe county, Xorth Carolina. 

The common garnet is met with in dodecahedrons, from 
three to four inches in diameter, at Fahlun in Sweden, 
Arendal and Kongsberg in ISTorway, and the Zillerthal in 
Tyrol ; in Mora\ia, Silesia, and Siberia ; in granular lime- 
stone at Haslan, near Eger, in Bohemia ; beautiful crystals 
of a rich brownish-red color, disseminated in hornblende 
gneiss, are found in Hanover, Xew Hampshire, in the 
United States; dark blood-red and splendid dodecahedrons, 
^vith. peached and truncated edges, at Franconia, 'New 
Hampshire, in geodes, in massive quartz, calcareous spar, 
and magnetic iron ore ; at Carhsle, Massachusetts, beautiful 
geodes of crystals of transparent cinnamon color, accompa- 
nying scapolite in white Hmestone ; at Monroe and Had- 
dam, Connecticut, imbedded in mica slate, also associated 
with chrysoberyl, beryl, automohte, and columbite ; large 
dodecahedral crystals, two inches and more in diameter, of 
a dark brownish-red color, at New Fane and Marlborough, 
in chlorite slate ; also in mica slate, in Chesterfield, Massa- 
chusetts. 

Colophonite is a granular brown variety, and is found in 
Arendal, jSTorway, and forms a large vein in gneiss at 
Willsborough, New York, on' Lake Chamj^lain ; a finer 
graded variety of yellow and red colors is found on 
Rogers' Rock, at Lake George. The colophonite is com- 
posed of coarse, roundish particles, oil-green and honey- 
yellow colors, and often possesses a fine iridescence. 

Allochroite is similar to colophonite, but the particles 
are impalpable and strongly coherent, 

lis 



260 A POPULAR TREATISE ON GEMS. 

Grossular has a pale gooseberry-green color (whence 
its name) ; in serpentine, with idocrase, in the Wilni river, 
in Kamtschatka. 

Topazolite is a honey-yellow garnet, in veins in ser- 
pentine ; has small yellow crystals ; found on the Mussa 
Alp, in Piedmont. 

Aplo'nie presents the form of the dodecahedron, but 
the facets are striated, parallel to the shorter diagonal; 
its colof is brown, sometimes greenish; from Sahla,- in 
Sweden. 

Melanite^ from fieXag, black, occurs in black dodecahe- 
drons, sometimes modified in volcanic rocks, on Monte 
Somma, in matter ejected by Vesuvius ; Frascati, Albano, 
near Rome, the Brisgau, in beds on the older rocks at 
Arendel, in Norway. 

Pyrenaite is found in minute, black, symmetrical dodec- 
ahedrons, and was so called from its locality in the Pyre- 
nees, and at the Pic Eves Lids, near Bareges. 

Ouioarovnte bears a close resemblance to the green 
garnet. It occurs in transparent emerald-green dodecahe- 
drons, with a hardness of 7*05 — harder than the garnet. It 
occurs at Bissersk, in Russia. •. 

The several varieties of garnet are quite diiferent in their 
composition ; they all contain silicate of alumina, and va- 
riable proportions of the silicates of lime, iron, and manga- 
nese, which substances have the property of replacing one 
.another without causing a change of crystalline form. The 
varieties of garnet are often classed as distinct species, such 
as almandine, pyrope, dodecahedral garnet, melanite, gros- 
sular, topazolite, aplome, essonite, cinnamon-stone, Green- 
landite, pyrenaite, colophonite, allochroite, Romanzovite, 
carbuncle, and ouwarowite. It is proper that garnet be 
divided into precious and common ; the first being the 
transparent, and the latter the opaque variety. The pre- 



GAENET. 251 

cious garnet, is again divided, according to its" transparency, 
into almandine and pyrope. As already stated, the dif- 
ferent varieties differ very little, and as the only import- 
ant species, possessing characters more distinctive than 
others from the garnet, is the cinnamon-stone, or essonite, 
the author has seen fit to separate it from the garnet, and 
to describe it under its proper head; moreover, essonite 
is more used by jewellers, when cut, than any of the other 
species of garnet, and as it has of late become fashion- 
able, it may be well to give a fuller description of the 
same. 

Garnet was the carbunculus of the ancients. This term 
was probably applied also to the spinelle and Oriental ruby. 
The alabandic carbuncles of Pliny were so called, because 
they were cut and polished at Alabanda ; hence the name 
almandine, now in use. 

In Bohemia, where there is a considerable trade in gar- 
nets, they are separated from the earth by levigatiori, 
then assorted into different sizes, afterwards washed again, 
and assorted as to color and quality, and according t^ the 
quantity required for balancing a certain weight, as half 
an ounce, they are called 32, 40, 76, 100; very seldom 
do they find them 16 to 20, weighing together half an 
ounce. 

The larger garnets are cut on the leaden wheel with em- 
ery, or their own powder, and polished with rotten-stone 
or oil of vitriol, on a tin plate, in the form of brilliants, 
roses, table-stones, or in cabochon, or with two rows of 
facets at the girdle ; and very often garnets are brighter 
and more agreeable by excavating them circularly on the 
bottom ; they are then called garnet-cups. I have in my 
possession several large excavated garnets, and I saw at 
Berlin, in 1828, such garnets of two and three inches size. 

Fine garnets are set d jour / others are set with a gold 



252 A POPULAR TREATISE ON GEMS. 

or violet ^oil at the base. Smaller gaiTiets are wrought on 
a large scale in manufactories for that purpose. They are 
perforated with the diamond, first, by means of a small 
point, then of a larger, and at last a finer point ; one hun- 
dred and fifty garnets may be perforated daily. 

The best garnets are cut in brilliant form, and with regu- 
lar facets, on a plate of fine sandstone, with sweet oil and 
emery. One man can finish thirty such garnets in one day. 
The polishing on wooden or leaden plates, with rotten-stone 
or oil of vitriol, is performed by women and children. 
More than twenty thousand garnets are yearly carried to 
market from a single manufactory. ' • 

Garnets are much worn in jewelry, as rings, breast j)ins, 
ear-rings, and necklaces; and sometimes snufi'-boxes are 
cut out of the larger ones from Greenland, Syria, or Tyrol ; 
the inferior pieces, unfit for cutting, are calcined and re- 
duced to powder, and employed as material for polishing 
other gems. 

The value of garnets is determined by their degree of 
perfection, as well as color, purity, and size. On account 
of their peculiarly deep 'color they must be cut very thin; 
and all such garnets as retain their fine color, without being 
cut too thin, are held in high estimation, and stand in value 
near the sapphire. A Syrian garnet eight and a half lines 
long, and six and a half lines broad, and cut octangular, 
w^as sold at the auction of the Marquis de Di'ee for three 
thousand five hundred and fifty francs. A fire-red oval 
Ceylonese garnet, eleven lines long and seven broad, was 
sold for one thousand and three francs. They are generally 
sold by the pound, containing from sixty to four hun.dred, 
valued at about eight to ten dollars per pound ; but a set 
of one thousand of the best selected garnets, well cut, is 
sold at about sixty dollars. Garnet is harder than idocrase 
or oxide of tin, but the latter is heavier, 



ESSONITE. . 253 

In the Mineralogical Museum of the Jardin des Plantes, 
in Paris, are some very fine garnets with engravings ; one 
is a mask of Silene, crowned with vine leaves; another is 
Calphnrnia's restlessness on the fate of Cciesar ; also the bust 
of Adrian, from the cabinet of Odescalchi ; the dog Syrius ; 
a head of Augustus, belonging to the Prince of Orange. 

Garnet is very well imitated by pastes, which are, 
however, softer and lighter, and diifer in many other 
respects. ~_^ * 

The following composition yields a superior imitation of 
the Syrian garnet : 

To 1000 parts strass, add 

500 " glass of antimony, 
4 " cassius purple, 
4 " oxide of manganese. 

ESSONITE, CINNAMON-STONE. 

This gem was formerly considered identical with Jiya- 
cinth^ under which name it yet passes in commerce and 
among manufacturing jewellers, and in France it is called 
hyacinth de Ceylon^ it is also called, in mineralogical 
works, cannel or cinnamon stone, which name it received 
from the Dutch gem-dealers, on account of its resemblance 
to the oil of cinnamon. Werner was the first who gave 
this stone the above name. 

Essonite occurs in crystals and grains; its fracture is 
conchoidal and uneven ; it is transparent and translucent ; 
has simple refraction of light ; the lustre is between vitreous 
and resinous ; its color is deep-red, hyacint^i-red, or or- 
ange-yellow; it scratches glass and quartz indifferently, 
but is attacked by topaz; its powder is white; specific 
gravity is 3'5 to 3'6 ; it becomes electric by rubbing; acts 
sometimes on the magnetic needle ; fuses easily before the 



254 



A POPULAR TREATISE ON GEMS. 



blowpipe into a clear greenish glass ;. borax and acids do 
not affect it. 

Essonite is found in the sand of rivers, and in the primi- 
tive rocks of Ceylon, in .considerable masses ; also in Scot- 
land. 

It is treated like garnet, by being cut on a copper 
plate with emery, and polished on a tin wheel with rotten- 
stone. It also receives the form of other gems, and when 
set, it is mounted Vith a foil answering to its color. 

It is used for rings and breastpins. Essonite is distin- 
guished from zircon by inferior hardness, smaller specific 
gravity, diminished lustre, and simple refraction of light. 
Garnet is heavier, and idocrase is lighter tlian essonite. 



TOURMALINE, RUBELLITE, SIBERITE. 

This mineral is as yet very little known among jewellers 
and the trade in general, although it has been in commerce 
for a number of years past,- but under other names, such as 
red tourmaline, or siberite, brought from Siberia, and sold 
in the trade as Oriental ruby. 

Tpurmaline was first introduced as a gem by the Dutch, 
who imported it from Ceylon. Tourmaline occurs in 
crystals and crystalline masses, and 
its forms are six, nine, and twelve 
sided prisms, with various trunca- 
tions and terminations, which com- 
monly differ in the number and size 
of the faces at the two ends. The 
crystals are long, striated, and com- 
plete, or aggregated into irregu- 
lar masses ; the fracture is conchoidal and uneven, semi- 
transparent to opaque. It has double refraction of light, 
which, however, is only visible in small pieces; it has a 




Fig. 9. 



TOURMALINE. 255 

vitreous lustre ; the colors are blue, red, green, and brown, 
of different shades. Several colors may often be observed 
in one and the same crystal, as, for instance, in the rubellite 
from Paris, in Maine, and Chesterfield, Massachusetts, in- 
closed by the green tourmaline ; and the color often varies 
in its different layers. 

Tourmaline scratches glass slightly, but is scratched by 
topaz ; its powder is white ; its specific gravity is 3'0 to 3'3 ; 
it becomes electric by rubbing, that end having the great- 
est number of faces being positive, the other negative. 
When tourmaline is heated it exhibits polarity, the most 
modified extremity becoming positive and the other nega- 
tive. In this particular it resembles other hemihedrically 
modified crystals. At a certain temperature it loses its 
polarity, but exhibits it again on cooling ; its polarity con- 
tinues with the decrease of temperature until it reaches 32°" 
Fahr. ; a continued increase of cold re-excites the electric 
polarity, though with reversed poles ; if the excited crystal 
be broken, each part thus produced will equally possess 
polarity, and even in the powdered state it retains its pyro- 
electricity. Before the blowpipe it intumesces more or 
less, does not fuse, but vitrifies on the edges ; turns green, 
then yellow, then red, then milk-white, then blue, and 
then black. Borax dissolves it pretty easily into a clear 
bead. 

The chemical composition of touraialines varies greatly: 
they are composed of alumine, silica, oxide of iron, oxide 
of manganese, and boracic acid ; those from different lo- 
calities contain either potash, soda, lithia, or calcia. The 
following are the-difierent varieties, not inckiding, how- 
ever, the white, yellow, and black tourmaline, or schorl, they 
not being used as gems : 

1. Siberian tourmaline (siberite, rubelhte, apyrite), which 
is of a carmine or hyacinth red, purple or rose red, passing 



256 A POPULAR TREATISE ON GEMS. 

into violet ; sometimes, by looking through in one direc- 
tion, the red color changes into a blue color. 

2. Indicolite (Brazilian sapphire), of an indigo, lazulite, 
or Pi'ussian blue color. 

3. Brazilian tourmaline (Brazilian emerald), of a grass- 
green or olive-green color. 

4. Ceylonian tourmaline (Ceylon chrysolite), of a green- 
ish-yellow color. 

5. Electric schorl, of a yellowish, reddish, liver, or black- 
ish brown color. 

Tourmaline occurs in rocks, such as granite in layers 
and gangues, and in boulders ; it also occurs in the beds 
of rivers, and the localities are Siberia, St. Gothard, Ceylon, 
Brazil, Sweden, Saxony, and Moravia. In the United 
States, tourmalines are abundant, but there are very few 
localities of the better varieties, as those at Paris in Maine, 
and Chesterfield and Goshen in Massachusetts. 

The specimen of a crystal of rubellite, from Paris, Me., 
on the frontispiece, is a perfect prism, is dark red on the 
inside and dark green on the outside, and belongs to Prof. 
Charles U. Shepard, of New Haven, who exhibited it in 
the New York Exhibition in 1853. There are several 
beautiful green and red transparent tourmaline crystals, 
from the same locality, in the mineralogical museum ol 
Yale College, from the collection of the late Baron Lederer, 
Austrian consul in this city. 

The yellow tourmaline, from Ceylon, is but little inferior 
to the real topaz, and is often sold for that gem. The green 
tourmaline, when transparent, is often highly prized. 

The Siberian red tourmaline, called siberite, is cut in 
cabochon, and exhibits then a milk-white chatoyant lustre. 

The black tourmaline is called schorl. The localities of 
tourmaline are quite numerous: large size black tour- 
malines are found in Greenland at Hovelberg, in Bavaria 



TOUKMALINE. 257 

near Bodfenmays, at Karinbrida in Sweden, and near Bo- 
vey in Devonshire. Small brilliant crystals are met with, 
imbedded in decomposed felspar, at Andreasberg, in the 
Hartz mountains, forming the variety called aphrigite. Ru- 
bellite occurs in a species of lithomarge, near Ekaterinen- 
burg in Siberia ; pale yellowish-brown crystals are found in 
talc at Windisch Kappell, in Carinthia; white and varie- 
gated colored specimens come from St. Gothard and Sibe- 
ria, the first imbedded in dolomite. 

In the United States, some magnificent specimens of red 
and green tourmalines were found in 1829 at Paris, State 
of Maine ; some transparent crystals from that locality ex- 
ceed two inches in diameter, and very frequently one inch, 
and present a clear red. color internally, surrounded by 
green, or are red at one extremity and green at the other. 
Blue and pink varieties, most commonly imbedded in lep- 
idolite, are yet occasionally found in this locality. 

Red and green tourmaUnes occur also at Chesterfield, 
Mass., in a narrow vein of granite traversing gneiss ; the 
crystals are commonly small and curved, nearly opaque, 
and exceedingly frangible. Green crystals often contain 
distinct prisms of a red color, especially when they occur in 
smoky quartz; blue tourmalines' also occur- at this locality, 
and are accompanied by albite. 

The Russian Mineralogical Museum was supplied, in 
1832, by its minister. Baron Crudner, with specimens of 
fifty pounds weight, containing the rock of green and red 
tourmalines, from the Chesterfield locality. 

At Goshen, Mass., similar varieties occur, and the blue 
tourmahne is met with in greater perfection ; very perfect 
crystals, of a dark-brown color, occur imbedded in mica 
slate, at Monroe, Conn. ; the crystals are commonly from 
one to two inches long, and nearly as broad, and uniformly 
they are perfectly terminated at the two extremities. 



258 A POPULAR TREATISE ON GEMS. 

Haddam, Conn., also affords fine black crystals, and some 
of large size ; they are profusely mingled in a mica slate, 
and associated with anthophylite and hornblaide. A cin- 
namon-brown variety is met with at Gouverneur, N. Y., 
imbedded with quartz, and also associated w^ith scapolite, 
apatite, and sphene, in granular limestone. These crystals 
are very often highly modified, and occasionally exhibit the 
faces of a scalene dodecahedron in addition to the terminal 
planes. Similar specimens occur at Grenville, Lowxr Can- ' 
ada, and Newton, N. J., associated with corundum, spinelle, 
and rutil ; and at Kingsbridge, N. Y., and Carlisle, Mass., 
with garnet. 

The red tourmaline, when transparent and free from 
cracks and fissures, admits of a high polish, and forms a 
most beautiful and costly gem. 

It has been supposed that tourmaline was known to the 
ancients under the name of lyncurium {XvvKovpiov)^ which 
is described as having electrical properties; this name, 
however, was more probably applied to some variety of 
amber, w^hich was so called from its supposed origin from 
the urine of the lynx. The identity of the red tourmaline 
with the hyacinth of the Greeks is more probable ; the 
other varieties were either unknown, or possibly connected 
under a common name with other species of the same color. 

Tourmaline received no attention from the moderns till 
Lemery, in 1717, published his discoveries. The word 
tourmaline is a corruption of the name for this mineral at 
Ceylon, whence it was first brought into Europe. 

The name schorl, which has been applied to the black 
tourmaline and some other mineral species, is reported to 
have been derived from Schorland, the name of a village in 
Saxony, which afforded specimens of this variety. 

Tourmaline is cut on a brass or leaden wheel with 
emery, and polished ^\\i\\ rotten-stone on a tin plate ; it re- 



QUARTZ. 259 

ceives various forms, such as the step and table cut. If of 
a pure color, it is set d jour^ otherwise with a foil corre- 
sponding to its color ; but the electric schorl is sometimes 
set so that it can be removed from its mounting to be used 
in performing experiments. The value of tourmaline de- 
pends upon its color^ purity, and size. The siberite and 
rubeUite stand highest in estimation. A siberite, as large 
as five lines, is worth about one hundred and fifty dollars ; 
and one of four to twelve lines, good color and pure, is 
worth about fifteen hundred dollars. The rubellite from 
Paris, Maine, has become very rare, and it is much to be 
regretted that no more attention is paid to obtaining a 
fresh supply, as the crystals are of an exceedingly fine 
purple color, and perfectly transparent. I have a few pol- 
ished rubellites and green tourmalines in my cabinet, which 
I value equally as high as any gems. 

The dark-green tourmalines, six lines long and four 
broad, are sold in Paris for eighty francs, and the light- 
green, of the same size, for forty francs. The most splen- 
did siberite is at the British Museum, having been pre- 
sented by the King of Ava to Colonel Symes ; it is valued 
at one thousand pounds sterling. 

Tourmalines may be readily ^distinguished from other 
gems or pastes^ which are sometimes substituted for them, 
by their property of assuming polaric electricity after being 
heated. 

QUARTZ. 

This mineral is diffused all over the globe. Its varieties 
are very numerous, and many of them are employed in 
jewelry and for divers ornamental jDurposes. It occurs 
massive, in concretions, in confused crystalline masses, and 
in crystals, of which the form is the six-sided prism, termi- 
nated by six-sided pyramids; also the dodecahedron, or 



260 A POPULAR TREATISE ON GEMS. 

double six-sided pyramid. Quartz scratches glass and 
felspar, but is attacked by topaz. Its hardness is 7*0, 
and its specific gravity, 2-5 to 2*7 ; it is transparent, and 
possesses a vitreous lustre ; becomes electric by rubbing ; 
is infusible before the blowpipe. Acids, except the fluoric 
acid, do not act upon it. Silica is the only essential com- 
ponent part of quartz, but some varieties contain iron, alu- 
mine, or lime. 

ROCK CRYSTAL. 

This mineral was known in early ages. It was highly 
esteemed by the Greeks on account of its purity and very 
regular formation. Theophrastes states that it was cut 
principally as seals, and the ancients made great use of it 
for ornaments, particularly before the art of making glass 
had reached much perfection. Among the many vessels 
which were cut in the form of cups, vases, &c., were two 
fine bowls and chalices in the possession of the tyrant Nero, 
who purchased them at a large sum. Rock crystal was also 
used as a medicine. 

It is found crystallized, in the primitive form, which is 
the rhomboid, extended to a six-sided prism ; and in a great 
variety of forms and modifications, such as with a trunca- 
tion or replacement of the edges, or solid angles, &c. It 
is frequently found in groups, also in the cavities of other 
minerals, or in incrustations, as small, but very perfect 
crystals, the pyramidal terminations of which have a high 
polish, and the specimen appearing as if it were studded 
with gems. Many specimens of this description were 
brought from Vermont a few years ago, and were eagerly 
purchased by the jewellers of this city for rings, ear- 
rings, and breastpins. Rock crystal has a conchoidal frac- 
ture ; is translucent and transparent ; possesses a double 
refraction of light; a perfect vitreous lustre; is limpid, 



EOCK CRYSTAL. 261 

white, brown, black, or yellow; scratches glass; specific 
gravity, 2*65. The electricity acquired by rubbing lasts 
for thirty minutes. Before the blowpipe, when colored,, it 
becomes limpid. The following varieties of it are made 
known by their names and characters : 

1. The pseudo diamond (Bohemian or occidental dia- 
mond), which is the limpid, colorless rock crystal, cut and 
polished. 

2. The iridescent quartz is that variety of rock crystal, 
the interior of which is replete with fissures and cracks, so 
that the refraction of the rays of light produce the rainbow 
colors. 

3. Citron (Bohemian topaz, occidental topaz, yellow 
quartz, Scotch pebble), which is of a pale, ochry, gold, 
whitish, lemon, or brownish yellow color. The false cairn- 
gouram of Brazil is a beautiful variety of yellow quartz. 

4. Smoky topaz (cairngouram or true Scotch pebble, 
brown quartz, smoky quartz) is of a smoky or brown 
color. 

5. Morion is of a charcoal-black or brownish-black color. 

6. Hair or needle stone, or such rock crystal as has, in its 
interior, foreign substances, as rutil (red oxide of titanium), 
manganese, iron, chlorite, amianthus, or asbestos. When 
the stone is so cut as to represent the hair or needles in an 
upright position, they are called either Venus' hair {cheveux 
de Venus) ^ or Love's arrows {flhches cPaonour). 

Rock crystal occurs in gangues, or rock cavities, in the 
oldest geological formations ; it is also occasionally found 
in some modern rocks. 

The mountain of Cairngouram, in Aberdeenshire, Scot- 
land, has furnished, and still continues to afford, many fine 
specimens of smoky quartz. The lapidaries of Edinburgh 
always meet with a ready sale of this far-famed stone 
among the Scottish gentlemen, as the native produce of 



262 A POPULAR TKEATISE ON GEMS. 

their country. Many very beautiful sets of the Cairngou- 
ram were exhibited in the London Exhibition. 

A group of rock crystal, in the museum of the univer- 
sity of Naples, weighs nearly half a ton. 

The black limestone of Quebec affords fine crystals of 
quartz. In the State of New York, quartz crystals, remark- 
ably clear and perfect, from the size of a pin's head to four 
inches, are found in many localities. Diamond Island, in 
Lake George, is a famed spot ; Gouverneur, N. Y., affords 
splendid dodecahedral crystals, associated with an irides- 
cent crystallized specular iron. At the Notch of the White 
Mountains, N. H., and at the locality of tourmaline at Paris, 
Maine, handsome crystals of brown and smoky quartz have 
been obtained. 

At Trenton Falls, in the State of New York, very per- 
fect and completely terminated transparent crystals are 
found, with their endless modifications, some of them five 
inches long, and some containing drops of water. It is 
also found at Windham, Vermont, Avhere the drusy variety 
occurs, which is extremely beautiful, and of variegated 
colors. About twenty years ago it had a great many ad- 
mirers, and was generally worn in brooches, rings, &g. 
.It is also found in Maryland, Massachusetts, and on the 
Catskill mountains. 

Rock crystal is obtained in Switzerland, and some other 
countries, by mining ; those cavities geologically or me- 
chanically traced from the quartz veins, are sounded by 
miners in granite veins or other rocks, by means of in- 
struments, and when hollow, extensive preparations are 
made for procuring the whole produce of the cavities, 
which sometimes amounts to several tons. It is likewise 
procured from the sand of rivers, and it passes then under 
the name of flints ; also, from gangues or veins of other min- 
erals. The smaller and clearer transparent ones are gener- 



EOCK CRYSTAL. 263 

ally employed in jewelry and for ornaments ; but the larger 
specimens are first assorted and then split or cleaved, and 
the smaller pieces are sawed through with a copper wire, 
emery, and oil, into the desired sizes, when they are ready 
for being cut on copper or leaden discs, with emery and 
water, and polished on tin plates with rotten-stone, putty, 
bole, or other fine powder ; or they may be polished on 
wooden wheels, fined with fur or leather. The forms which 
they generally receive from the lapidary, are the brilliant, 
rose, or table. The iridescent quartz, and the hair or 
needle stones, are only cut concave. Those specimens that 
have a full pure wine-yefiow color, are best cut in steps. 
When mounted, they are either d.jour, or with a black 
foil. Those which are spotted, or of an irregular color, 
may be discolored by careful calcination in crucibles, with 
Hme, sand, or pearlash, which process likewise increases the 
lustre. The crystal may be bored with a diamond point, 
also engraved, and figures may be etched in it by means of 
fluoric acid. It is mostly used for pins and rings ; also, for 
the base of doublets ; likewise, for a very great variety of 
ornaments, such as seals, gems, snuff-boxes, cane-heads, &c. ; 
also for imitating the real gems, by being colored and 
immediately immersed in a solution of coloring water, 
whereby the color is very closely imitated. It is moreover 
the base of all the pastes or strass. 

Its value is by no means so high as formerly, when the 
•demand for it was great for setting in buckles, buttons, 
&c. Articles made of large pieces of ^ it, or those con- 
taining slender needles, hair, moss, incrustation, or imita- 
tion of other substances, are yet somewhat esteemed. In 
their natural state, if quite clear, as they are received from 
Madagascar, Switzerland, and Brazil, they are sold for from 
one to i;en dollars per pound ; but when cut for seal-stones, 
or breastpins, they are sold mostly by the jewellers of this 



264 A POPULAR TREATISE ON GEMS. 

country as white topaz, and command a fair price. WelP- 
cut seal-stones are sold at from five to twenty dollars. 
Those of the brilliant-cut are sold at from fifty cents to a 
dollar a piece. The largest rock crystal is said to be in the 
collection of M. Rafaelli, artist, at Rome, — and a large can- 
delabra of iridescent quartz, is in the Vatican. The proprie- 
tors of the American Museum of this city, can boast of 
having one of the largest specimens of rock crystal from 
Brazil. It weighs two hundred and twelve pounds, is two 
feet and a half high, and one foot in diameter, and is a 
perfect six-sided prism. 

Two latge crystals of quartz, attached by one of the 
vertical faces, the crystals being each two and a half feet 
high by eight inches in diameter, were exhibited .by the 
Duke of Devonshire, at the London Exhibition, in 1851. 
The pyramidal summits of these crystals, which rise neai'ly 
a foot above the prism, are completely transparent, but the 
prisms are cloudy. These magnificent crystals were ob- 
tained from the Alps, having been discovered during the 
formation of the road over the Simplon, in a cutting made 
through the old rocks. I saw a most magnificent chandelier 
of rock crystal in the Tuileries, which is said to have cost one 
hundred thousand francs. The clearest rock crystal comes 
from the island of Madagascar, in blocks weighing from 
fifty to one hundred pounds. In Switzerland, and the prov- 
ince of Auvergne, in France, very fine specimens may be 
had. The Bristol, Buxton, Cornish, and Irish diamonds, 
which are all pyramidal crystals of quartz, are known all 
over the world. 

A specimen of rock crystal in the Museum of Natural 
History, at Paris, measures three feet in diameter, weighs 
nearly eight hundred .pounds, and was found at Fischbach, 
in France. 

Rock crystal may be easily distinguished from white 



ROCK CRYSTAL. 265 

paste, called strass, as the latter is heavier, on account of 
the metallic oxides contained in the composition. 

A very remarkable phenomenon in quartz is exhibited / 
by the fluid drops which are contained in many speci- / 
mens. They occupy small cavities, and evince their pres- 
ence, on turning the specimens, by the motion of the accom- 
panying air-bubble, like the bubble in a spirit-level. These 
cavities are sometimes of considerable size. Jacobson, of 
Copenhagen, possesses a geode of quartz an inch and a 
quarter long, whic?i contains at least half a cubic inch of 
fluid. Mr. Allen also describes a crystal of amethyst in his 
collection, which contains four cavities partially filled with 
this peculiar fluid. At a temjDerature of eighty-three de- 
grees the fluid dilates and entirely fills all the cavities, and 
as it re-appears on cooHng, an ebullition is apparent. Sir 
David Brewster has ascertained that the fluid is not, as 
was supposed, water, but of an oleaginous nature, from 
twenty to twenty-five times thinner than water. A consid- 
erable number of specimens containing the fluid were 
carefully examined, and he found that one part of the fluid 
is volatile at twenty-seven degrees, and the other was a 
fixed oil. Prof Dana has lately named the former, crypto- 
line, and the latter, brewsterline. There is a great difierence 
in the specific gravity of both liquids. The more dense 
yields a transparent yellow resinous globule, which absorbs 
the humidity of the atmosphere, is insoluble in water and 
alcohol, but dissolves in hydrochloric and nitric acids. 

Occasionally a bituminous fluid, resenibling naphtha, is 
contained in the cavities of quartz. 

A very peculiar gelatinous substance, appearing to be 
silica in solution, has been observed on breaking open 
geodes, and the production of a species of chalcedony from 
the subsequent evaporation, has also been observed. But 
the nature of the solvent of silica is not yet fully ascer- 

12 



266 A POPULAR TREATISE ON GEMS. 

tained. It is, however, held in solution in the "hot waters 
of the Geysers of Iceland, whose solvent power is supposed 
to be due to the presence of a small quantity of an alkali 
and their high temperature. The Geysers have covered 
the part of Iceland in their vicinity with a silicious sinter. 

The pseudomorphous quartz, from North Carolina, con- 
tains fluids in large quantities in its cavities. 

Two pieces of quartz rubbed ^together in the dark, emit 
a phosphorescent light and a faint empyreumatic odor. 

AMETHYST. 

This gem has been known since the earliest ages of 
Greece and Rome ; the name is of Greek origin. The 
ancients believed that wine drank from an amethyst cup 
would not intoxicate ; hence its name, expressive of that 
belief — afiiOvorog^ from a, not ; fMedvo)^ to intoxicate. As re- 
gards the color, Pliny says : "ad riciniam crystalli descen- 
det albicante purpuras defectu," purple gradually fading into 
■white. This is not, however, the only amethyst of the 
ancients ; the violet-colored sapphire, the violet fluor spar 
(" sculptaris faciles," easily graven — Pliny), and some other 
purple species, were designated by the same name. It has 
also been supposed that garnet came under the same de- 
. nomination. This name occurs in Scripture, being that of 
the ninth stone in order on the high-priest's breast-plate of 
judgment, with the name Issachar engraved thereon. 
Amethysts were always used for engraving. The bust of 
Trajan, in the Royal Library, at Paris, and the Apollo 
Belvidere, the Farnese Hercules, and the group of Lao- 
coon, are splendid specimens of it. It occurs massive in 
boulders, or in hexahedral prismatic crystals, terminated 
by hexahedral pyramids. Its crystals are rarely as distinct 
as those of quartz, being, for the most part, laterally aggre- 



AMETHYST. 267 

■ ■• 

gated by the whole prism, the terminal pyramids alone 
being separated from each other ; its fracture is from con- 
choidal to splintry; it is transparent to translucent ; of a 
vitreous lustre ; color, of a high and dark violet-blue, and 
fi'om its richest tinge to almost colorless, in one and the 
same specimen. It scratches white glass, gives fire with 
steel, but yields to'the file. Its specific gravity, 2 'To ; be- 
comes electric by rubbing, which lasts, however, but half 
an hour. Before the blowpipe it loses its color. Its compo- 
nent parts are pure quartz, colored by manganese and 
iron. It occurs in veins of the older formations, studding 
the interior of agate balls or geodes in the amygdaloid and 
trap rocks of Hungary, Silesia, Saxony, Tyrol, Oberstein ; 
and as boulders of splendid specimens in Ceylon, Siberia, 
and Brazil. It is wrought in the same manner as rock 
crystal, being cut on a copper wheel with emery, and pol- 
ished on a tin plate with rotten-stone. In order to raise 
its lustre, many facets, and very frequently those of a rose- 
diamond, are given to it in cutting. It is sometimes cut in 
the form of a brilliant, and when set is supplied with a blue 
or red foil, provided the amethyst is pale, for the deep- 
colored ones do not require any artificial assistance. It is 
used in almost every description of jewelry, such as rings, 
ear-rings, and breastpins; but it is set in necklaces to 
the best advantage, and is the only colored gem which 
may be worn with mourning, an advantage which adds 
to its value. The amethyst is no longer held in such 
estimation as formerly, but the color, when intense and 
uniform, as also the size, contribute greatly to its value; 
and good well-cut amethysts, of one carat, are worth from 
three to five dollars, and so on, in pro]*ortion to their size : 
an amethyst fifteen lines long and eleven lines broad, ex- 
quisitely fine, was valued at five hundred dollars. 

The best amethysts now in commerce come from Cey- 



268 A I'OPULAR TREATISE ON GEMS. 

Ion, Siberia, and Brazil ; the first? are commonly called 
Oriental amethysts, which, however, must be carefully 
distinguished from a much more valuable gem, the true 
Oriental amethyst, which is the violet sapphire. I have 
in my collection a quantity of the Brazilian amethysts, 
which are of an intense violet color, and of a very large 
size. . ' 

Amethysts occur also at Pic Bay, and at Gorgontwa, 
Lake Superior, crystallized in trap ; also at Bristol, Rhode 
Island, and occasionally throughout the trap region of Mas- 
sachusetts and Connecticut. 

The amethyst is valued by the jeweller in proportion 
to the depth, richness, and uniformity of its color, and 
its perfect transparency ; it forms, then, a stone of ex- 
quisite beauty, its color being, perhaps, more generally 
attractive than that of any other gem, especially as it may 
be obtained of as large a size as can be conveniently worn. 
It is worn by priests, bishops, and pontifical dignitaries 
as a ring-stone set with brilliants. Like many other stones, 
it is less brilliant by candle-light, and it appears at all 
times to best advantage when surrounded with pearls and 
set in gold. 

Amethyst has lately been employed by the cameo-cutters 
of Paris, for cameos and intaglios ; the head is cut at the 
collet, which is the thick part of the stone, and the crown 
having diamond facets produces a fine effect. 

The amethyst is often imitated by fluor spar or violet- 
blue lime spar ; both, however, are softer than amethyst : 
the lime is lighter, and the fluor is heavier than amethyst. 
But it is imitated very strikingly by pastes, so that with 
great difficulty the real is to be distinguished from the 
imitation ; the latter, however, is somewhat heavier, on ac- 
count of the metallic oxides contained in the composition. 
The following is the best receipt for imitating the amethyst : 



COMMON QUARTZ. 269 

1000 parts of strass, 

8 " oxide of manganese, 

0*2 " purple of cassius, and 

500 " oxide of cobalt. 

One of the largest geodes of amethyst was brought 
into England in 1819, weighing one hundred and fifty 
pounds ; it was two feet long and fourteen inches broad, 
and contained most magnificent crystals, of the deepest 
violet color. On account of having been set down at too 
low a price at the custom-house, which was sixty-five 
pounds sterling, it was confiscated. 

COMMON QUARTZ. 

But a few varieties of the common quartz are used in 
jewelry, which are: the Bose Quartz, the CaPs-eye, the 
Prase, and the Avanturine. 

Hose Quartz. 

This mineral generally occurs massive; is semi-trans- 
parent, and translucent on the edges ; has a vitreous lustre ; 
conchoidal and splintry fracture; is of a rose-red color; 
sometimes giving a lustre of mother-of-pearl. It scratches 
glass ; has a specific gravity of 2*64 to 2*67 ; its color, which 
is derived from the oxide of manganese, becomes paler 
before the blowpipe. 

.Rose quartz occurs in gangues of granite and gneiss, 
particularly fine in Sweden, Bavaria, Bohemia, and Siberia ; 
also of a beautiful dark color in New Hampshire and Mas-I 
sachusetts. ' » I 

Rose quartz is cut and polished for jewelry; such as 
rings, breastpins, and snufi'-boxes; it is cut on a copper 
wheel with emery, and is polished with rotten-stone and 
putty, on a tin plate, receiving the form of a cabochon or 



270 A POPULAR TREATISE ON GEMS. 

table, and when set requires a foil, colored by carmine or 
solution of gold, as it fades when exposed a long time to 
the light. The rose quartz is not held in great estimation ; 
the color as well as the lustre of faded rose quartz may 
be resuscitated by being left for some time in a moist 
place. 

A vase of rose quartz was in the possession of the Mar- 
quis de Dree, nine inches high and two inches in diameter. 

Cafs-eye. 

The name of this mineral is derived from the peculiar 
play of light perceptible on its surface, by which it re- 
sembles the rays of light in the eyes of a cat ; it is not 
ascertained whether the ancients knew this mineral, and 
whether it was comprised in their asterias; but it is well 
known that cat's-eye is in high estimation among the 
Malabars and Moors ; and it is worn throughout the whole 
East, where it is employed as an amulet, being believed to 
possess the virtue of enriching the wearer. 

Cat's-eye occurs massive, and in more or less roundish 
pieces ; has a conchoidal fracture ; is translucent and trans- 
parent sometimes on one end; it has a shining lustre, 
between vitreous and resinous; gray and brown, green, 
red, and yellow color ; it presents a peculiar floating light, 
which is particularly visible if cut in high cabochon, as it 
usually is w^hen brought to market ; it scratches glass ; h{\s 
a specific gravity of 2*56 to 2''73, and contains 95 silex, 
1*75 alumina, 1"50 lime, and 0'26 oxide of iron. In many 
specimens, there may be tobserved small parallel white 
fibres, which are supposed to be the cause of its peculiar 
play of light ; but the semi-transparent varieties, which 
are equally chatoyant as the more opaque ones, present 
no such appearance. This leads to the conclusion that 



COMMON QUAETZ. 271 

amianthus in its finest fibres occasions the phenomenon, 
and the chemical analysis of the latter corresponds with 
the additional constituents of the cat's-eye. By exposure 
to a strong heat, it loses its lustre and transparency ; and, 
in small fragments, is fusible before the blowpipe. Cat's- 
eye is found in fragments of gangues and boulders, of 
very small size, never larger than a hazel-nut, in Ceylon, 
on the coast of Malabar, in the Hartz mountains, Bavaria, 
and in this country (in Vermont, New York, &c.) Ceylon, 
where the finest cat's-eyes are found, sends them abroad 
already cut and polished in cabochon ; but very often they 
are cut over again on a copper wheel, with eniery, and 
polished on a tin plate : they receive in setting a gold foil. 
The value depends principally upon its intrinsic properties, 
size, color, and degree of play of light. Of the nearly 
opaque varieties, the red and the almost white are the most 
esteemed, and such are sold usually from ten to twenty 
dollars ; and a stone of the size of a square inch, and other- 
wise perfect in its properties, is worth from eighty to one 
hundred dollars. 

In the imperial cabinet of Vienna, a cat's-eye, five-inches 
in length, of a yellowish-brown color, may be seen. 

The Indians attribute to cat's-eye wonderful virtues, and 
the largest and prettiest stones are said to possess them 
in a high degree. 

Jean Ribeiro quotes, in hisJ' History of Ceylon," a cat's- 
eye, belonging to the Prince of Ura, which was perfectly 
round and of the size of a pigeon's egg, possessing mag- 
nificent chatoyant colors ; changing, on the least movement 
of the stone, its beautiful reflections. 

Prase. 

This mineral is mentioned by Pliny ; but it is not 
certain whether he meant the same substance that we do : 



272 A POPULAR TREATISE ON GEMS. 

more probably he alluded to the emerald ; for the sapae 
mineral is at the present time called the emerald mother 
or matrix by jewellers. Prase occm'S massive and crys- 
tallized ; it has a conchoidal fracture ; is translucent on the 
edges ; between vitreous and resinous in lustre ; and of a 
garlic-green color, the cause of which is, that actinolite is 
intermixed with the silex. It scratches glass, has a specific 
gravity of 2*66 to 2*88, and is composed of silex, alu- 
mina, and oxides of iron and manganese. It is found in 
Saxony, Tyrol, Styria, Hartz, and the island of Elba. It is 
used for rings and pins; also, for snuff-boxes and other 
jewelry, and is cut in cabochon, and set with a gold foil at 
the base, by which its color is heightened, and rendered 
more agreeable. It is used in mosaic works, for foliage ; 
and likemse in the mounting of rubies, in order to raise 
their color. Prase does not stand in great estimation ; 
for although it assumes a yery good polish, it loses the 
same on long exposure to the air, and grows spotty. 

Ava7iturine. 

This mineral received its name from bearing a resem- 
blance to a glass paste, formerly manufactured in Italy. It 
is a brown or red quartz, which is massive and translucent, 
or opaque ; it has a resinous lustre, and its fracture is splin- 
try and uneven ; it is penetrated with gold or brass-yellow 
glistening fissures, caused by the refraction of lightj or by 
innumerable mica leaves. It scratches white glass ; has a 
specific gravity of 2' 6 4 to 2*68 ; silex, with some alumina 
and water, are its constituents. 

The avanturine is found in the Uralian mountains, Styria, 
Cape de Gata, near Madrid, Nantes, Scotland, &c. It is 
used for ring-stones, ear-rings, and snuflT-boxes. It is cut 
on a copper wheel, with emery, and polished with rotten- 



JASPER. 273 

stone on a tin plate ; it is cut semi-lenticular or oval, does 
not take easily a good polish, but may be improved by 
rubbing the stone with oil of almonds. The value of 
avanturine is much depreciated of late, and its imitation 
by glass paste, called goldstone^ is by far superior to the 
real stone, which has nothing but hardness in its favor. 
This paste is manufactured in great quantities in France, 
by throwing the finest impalpable powdered brass into 
a quantity of colorless strass, or into ^ composition of 
•105 parts quartz, 

85 " purified potash, 
230 " tin and lead alloy, 
50 " brass powder. 

The artificial avanturine, as made in Italy, is a silicious 
oxide of copper. The mode of manufacturing the best 
quality, which is done very extensively in Italy and France, 
is still kept a secret ; that the copper is reduced first to a 
sub-oxide, and nearly to its crystalline metallic state, may 
be inferred on examining with a microscope the common 
•artificial stone, which has a most splendid appearance. 
The best avanturine is manufactured in Venice, by M. P. 
Bibaglia, who alone appears to have the secret of excelling 
the natural stone. Messrs. Fremy and Clemendot, expert 
French chemists, have succeeded in approximating the Ve- 
netian manufacture, by heating 3Q0 parts ground glass with 
40 parts of protoxide of copper and 80 parts of oxide of 
iron, and allowing the mass to cool very slow. 

Large blocks of the factitious avanturine, with a great 
variety oi manufactured ornaments, were admired in the 
Paris Exhibition, in 1855. 

JASPEE. 

This mineral is of Oriental origin, and is very often men- 
tioned in the Bible. It was the sixth stone in the plate of 

12^> 



\ 



2 '74 A POPULAR TREATISE ON GEMS. 

the high-priest. Jasper was well known to the Greeks and 
Romans, and according to Pliny, who has described sev- 
eral varieties, the best came from Scythia, Cypria, and 
Egypt, on the banks of the Mle. The lapidaries formerly 
made use of it in their works, particularly the Egyptian 
jasper, which afforded them abundant material. The col- 
umn of Memnon and the foundation of the column of Pora- 
pey were constructed of it, and we find daily, among the 
excavations of Her<?ulaneum and Pompeii, fragments of 
ruins, composed of Egyptian jasper. 

Jasper occurs in enormous masses; has a conchoidal 
fracture ; is opaque ; its lustre is slightly resinous, like wax, 
often dull ; it is of white, red, yellow, green, blue, brown, 
and black colors; it scratches glass, but yields to rock 
crystal; its specific gravity is 2*31 to 2*67. 

It is usually found in gangues, seldom in strata, in Egypt, 
Bohemia, Saxony, Tyrol, Hungary, France, Italy, Spain, 
Siberia, Corsica ; in the United States, principally in 
Florida, North Carolina, Massachusetts, &c. ; also in Nova 
Scotia. 

A fine yellow" jasper is found at Yourla, bay of Smyrna, 
in a low ridge of limestone, to the right of the watering- 
place, between the harbor and the high hills that commence 
their rise about a mile back; it is here associated with a 
beautiful opal, coarse carnelians, chrysoprase, and horn- 
stone, and these minerals seem to occupy in the limestone 
the place of hornstone, which is found in various parts of 
the adjoining country, and also at Napoli di Romania, in 
Greece. The plains of Argos are strewed Vith pebbles of 
red jasper. 

The jasper and quartz rocks of Siberia are well known 
materials of extreme hardness, worked only in the Russian 
empire, and are rarely met with, except as imperial pres- 
ents to princes and distinguished foreigners. A group of 



JASPER. 275 

very remarkable objects was exhibited among the Russian 
goods in the London Exhibition. The material of some of 
these vases is quartz rock, but most are of a kind of pseudo 
.jasper or pseudo jasper lava, of greenish color, and extreme 
toughness and hardness, resisting almost every tool,' and 
requiring to be cut with emery, like the hardest gems. 
These rocks chiefly exist in Siberia, beyond the Oural, and 
are in great abundance and variety. The vases of jasper 
were worked at the imperial manufactories of Ekaterinen- 
burg and Kolyvan. There almost the whole work is per- 
formed by manual labor ; the only machine used is a simple 
lathe, on which the object to be turned is placed, and 
worked by iron tools and emery. . ISTo tool will touch these 
stones, both chisels and files of the hardest temper turning 
without producing any effect. The time for furnishing 
vases of considerable magnitude is often many years, and 
their value is calculated by the cost of the large estabhsh- 
ment kept at constant work. A large vase, measuring three 
feet on each side, in a square ^orm, was exhibited, hollow 
under the rim, with foliage in the same,, and was one of the 
great curiosities in the Exhibition. Smaller vases, an 
olive-green jasper ura, decorated with admirably worked 
foliage in relief, from the imperial manufactories, were like- 
wise exhibited, all of which excited the admiration of the 
spectators ; and since the times of the Greeks and Romans 
no such gigantic works, both in dimension and weight, 
have been wrought. The quantity of intaglios and cameos 
from the ancient Greeks and Romans is too numerous for 
giving them a space in this treatise, for it would fill a whole 
book to specify the antiques which are scattered around 
the world, in the various museums of Rome, Vienna, Paris, 
London, Berlin, Dresden, and the private cabinets which 
have for centuries existed in noble famiUes. 

According to their varieties, which are yery numerous — 



276 A POPULAR TREATISE ON GEMS. 

that is, in color and structure — they receive their names; 
but they may still be classified into the following two 
divisions : 

1. Egyptian Jasper (Egyptian pebble), which occurs- 
in spheroidal pieces, of a gray-brown or red color, the 
form of which is cut and polished in annular represen- 
tations around its centre. It is found in Baden, Up- 
per Egypt, and other places ; among the pebbles of the 
river Nile it is frequently discovered; and in the year 
1714, it was found near the village of Incheric, by Paul 
Lucas. 

2. Ribbon or Striped Spar. It occurs in masses, with 
nearly conchoidal fracture, around which parallel, straight, 
or twisted stripes of a gray, green, yellow, red, or brown 
color may be perceived ; it is principally found in Siberia, 
the East Indies, Corsica, Tyrol, and the Hartz mountains ; 
some of the West India islands produce most splendid 
specimens. 

Jasper is principally used for seals, snuff-boxes, vases, 
tsible-plates, and for some architectural purposes. 

When in lumps, it is di\ided by means of copper saws 
and fine sand, and then cut on copper or leaden wheels 
with emery, and polished on tin plates with rotten-stone, 
colcothar, or charcoal ; or it may first be polished on wood 
with pumice-stone, and lastly on a tin plate with* rotten- 
stone and water. 

The yellow jasper is often employed in mosaic works in 
Italy, and the striped jasper as cameos. Jasper has no 
great value in trade, unless it be of exquisite quality, and 
fine objects be made of it. It generally commands the 
best price in China, where the emperor has a seal cut of 
it. A vase of red jasper, with white veins, and one of 
black jasper, with yellow veins, may be seen in the Vati- 
can. Chatouilles and other boxes of considerable size 



CH ALCED ON Y. 277 

are frequently found in the jewelry stores of France, Eng- 
land, and the United States. • 



HOENSTONE. 

Hornstone occurs massive, globular^ stalactiform, and in 
pseudo-morphous crystals of carbonate of lime, and also in 
the form of petrified wood (wood-stone or agatized wood). 
Its fracture is either conchoidal or splintry ; it is opaque or 
transparent on the edges; has a dull or shining lustre; 
deep gray, brown, red, yellow', or green, and rarely a pure 
color. Often it has several colors in one and the same spe- 
cimen, such as points, spots, and stripes. It scratches 
glass, and has a specific gravity of 2'53 to 2'65. 

It is mostly found in gangues of the older formation ; 
also in the old red sandstones and alluvial formations, in 
Bohemia, Saxony, Sweden, Siberia, Hungary, and a number 
of other places ; in the old red sandstone of Thuringia. I 
have traced one stem of the red agatized wood eighteen feet 
in length and two feet in diameter. The price of hornstone 
is very low ; it is used for snuif-boxes, seals, crosses, mor- 
tars, and principally as knife and fork handles. It is now 
used by silversmiths to mount butter and dessert knives 
and forks, which are imported from Germany in consider- 
able quantities. 

CHALCEDONY. 

♦ 

This mineral was held in great estimation by the an- 
cients, who received their principal supplies from Egypt 
and other parts of Africa. In Rome, much use was made 
of it for cameos, many of which may yet be seen in col- 
lections. The inhabitants of Iceland are likewise said to 
value it very highly, and to attribute many medicinal pro- 



278 A POPULAB TREATISE ON GEMS. 

perties to it. It is found in crystals, such as cubes, but 
mostly massive, botryoidaf, stalactiform, globular, or reni- 
form, &c. The fracture is even, sometimes running into 
conchoidal or splintry; it is semi-transparent or translu- 
cent, of Uttle lustre, or dull ; of white, gray, blue, yellow, 
brown, or green colors, which are all of a light shade, and 
variously figured, striped, spotted, &c. 

It scratches white glass, and has a specific gravity of 
2*58 to 2*66. It is distinguished into the following varie- 
ties, viz : 

1. Chalcedony proper, or chalcedony x, wherein white 
and gray stripes alternate with each other. 

2. Mocha or tree stones, are such chalcedonies as display 
black, brown, or red dendritical figures. 

3. Rainbow or agate chalcedony, is chalcedony of thin 
and concentric structure, which, cut* across and kept to- 
wards the light, displays an iridescence. 

4. Cloudy chalcedony, has a light gray and transparent 
base, with dark and cloudy spots. 

5. Plasma, dark grass-green. This mineral was very 
often employed by the ancients for cutting. ^ -' 

6. Semi-carnelian, or ceregat, is generally called the yel- 
low chalcedony. 

7. Sappharine, is the sky or sapphire blue chalcedony. 

8. St. Stephen's stones, is the white chalcedony, with 
blood-red spots. 

There are many more varieties, and in my own collection 
I have polished chalcedonies, among which, perhaps, as 
many again may be enumerated. 

Chalcedony wa* originally procured from Chalcedon, in 
Asia Minor, whence its name. 

Chalcedony is found in gangues, and in the cavities of 
many rocks ; also in boulders and pebbles. Localities exist 
in Saxony, Hungary, Faroe Islands, Ceylon, on the shores 



CAENELIAN. 279 

of the Nile, in N'ubia, Nova Scotia, the United States (in 
Connecticut, Massachusetts, Pennsylvania, Ohio, New Jer- 
sey, Missouri, Florida), and in other countries ; but the 
best specimens are brought from Oberstein, Iceland, and 
the Faroe Islands. 

The finest specimens are employed in jewelry, for rings, 
pins, bracelets, necklaces, and seals ; the more common for 
snuff-boxes, vases, buttons, &g. The larger masses are cut 
by means of a copper wire, with emery and oil on a copper 
wheel ; they are polished on a tin plate with rotten-stone, 
putty-powder, and pumice-stone. The cutting is generally 
done on a large scale, like that of agate. Many are sus- 
ceptible of receiving figures artificially, by means of the 
nitrate of silver. By Oriental chalcedony is generally un- 
derstood the better qualities ; those chalcedonies of two or 
three divisions, called onyx, are used for cameos. 

The value of the chalcedony depends on its quality, such 
as purity, color, and the figures and drawings displayed on 
it ; and among all the varieties of chalcedony, the mocha 
stone stands the highest in price, and also the onyx, which 
is principally employed for cutting cameos, and according 
to its size, commands a high or low price. Mocha stones 
are sold in France at from five to eight francs. The cabi- 
net of Dresden contains a plate of onyx, about three inches 
broad and long, which is estimated at twenty-five thousand 
dollars. 

CAENELTAISr. 

This stone was known to the ancients by the name of 
Sarda ; which, according to some, is derived from a place 
in Lybia or Sardinia, or, according to others, from the 
Arabic word sarda, meaning yellow ; it has been employed 
very frequently for cutting intaglios or bas-relief gems. 

Carnelian occurs massive or in pebbles ; its fracture is con- 



280 A POPULAR TREATISE ON GEMS. 

choidal ; lustre resinous ; it is semi-transparent and trans- 
lucent ; of a blood-red, yellow-brown, or yellow color ; 
frequently dark at the outside, growing paler towards the 
inside; the colors are sometimes changing striated; it 
scratches white glass, and has a specific gravity of 2'59 to 
2'63. There ai;^ two varieties known by lapidaries and 
jewellers which are better than the others ; those having a 
pale color or yellowish tinge, and those having a dark-red 
color; the latter are in the highest estimation, and are 
called by the French cornalines de vieille roche. 

Sardonyx is called a carnelian, having as its principal 
color the dark-brown or orange-yellow, interchanged with 
layers of a white color. 

Carnelian onyx, has a blood-red base, marked with white 
stripes. The finest carnehans come from Siberia,* India, 
Arabia, Nubia, Surinam, Oberstein in Germany, and Tyrol ; 
they occur mostly as pebbles or in cavities of rocks ; in the 
United States, they are found on Lake Superior in large 
quantities, in Missouri, and in Massachusetts. The carne- 
lian is used for numerous articles in jewelry, such as seals, 
rings, watch-keys, &c. ; it is cut on a leaden plate with 
emery, and is polished on wood with pumice-stone, and ob- 
tains its highest polish on a plate composed of lead and tin 
with rotten-stone and water. The form of its cutting is 
that of pavilion or step cut, on the upper part, and either 
quadrangular, hexagonal, octangular, or round; and for 
raising its lustre or color it is furnished with a silver or 
gold foil, or with red paint on its base. The color of the 
carnelian is also improved by calcination ; the yellowish 
kind, for instance, by calcining it in a moderate heat and 
cooling it slowly, may assume a good red color. It is said 
that the ancients boiled the carnelian in honey in order to 
heighten its color. Colored figures or drawings may sitc- 
cessfully be represented by a mixture of white-lead, colco- 



CAEKELIAN. 281 

thar, or other metallic oxides and gum-water, which is the 
material for drawing on it, and by burning the same under 
a muffle. 

Carnelian is divided into Oriental and occidental: the 
first is found in the old rocks, and is generally very hard, 
rich in color, clear and transparent, and takes a high" 
polish, is brought from Surat, in the Indies, and valued at 
ten francs the kilogramme ; the occidental carnelian is 
softer, of a yellower red, and less brilliant. 

Stygmite is a beautiful variety with variegated colors, 
of reddish-yellow or yellowish-red, with many white Hues 
passing through the stones. • 

The ancients, particularly the Romans, were very partial 
to engraving on carnelian, and some very remarkable stones 
are still in existence in the imperial library at Paris. The 
seal of Michael Angelo, which is valued at 50,000 francs, 
is said to have been engraved by Maria de Descias after 
the original of Praxiteles ; the bust of Ulysses, Hercules 
killing Diomede, Jupiter, Mars, and Mercury. 

The great scarabee in carnelian, in the Prussian cabinet, 
which represents the five heroes of Thebes, is a master-piece 
of Etruscan art. 

The crown-jewels of France contain some very costly 
carnelian engravings of very large size. 

The faults of the carnelian are fissures, unequal color, 
and flaws from other stones. Carnelian is, on account of 
its being less brittle, more useful for engraving and cut- 
ting cameos ; the white layers are generally used for the 
figures of cameos and the red for the base. Sometimes 
such carnehans as are cut with bas-relief objects, are filled 
out with colored strass; and we receive from India, very 
frequently, cameos with the most singular drawings, and 
Which are made by the inhabitants in the foltewing manner : 
the whole carnelian is covered with carbonate of soda, and 



282 A POPULAR TREATISE ON GEMS. 

then exposed to the fire for a few minutes, whereby a strass 
is formed, upon which the figures are cut. The vahie of 
carneUan is much higher than chalcedony, but yet depends 
on all its qualities of color, transparency, equal division of 
color, and freedom from faults, such as fissures, clouds, 
dark spots, &c. For a perfect sardonyx, a very high price 
is generally given, particularly when the layers are very 
distinct and run quite parallel, and are pretty thick, so 
that they are fit for cutting cameos or intaglios. The 
blood-red is second in value, and the pale-red, third ; but 
the cheapest are the yellowish, brownish, or whitish kinds ; 
the prices vary from twenty dollars to twenty cents per 
piece. There exists a cameo of sardonyx, representing the 
portrait of the celebrated Father Fontanarosa, having his 
face white, with the base, cap, and cloak black, so that it 
may distinctly show the Dominican monk. 

HELIOTROPE, BLOODSTONE. 

This stone derives its name from the Greek language, 
having been used in ancient times for observing the sun ; 
Pliny speaks of heliotrope. It occurs in massive and 
obtuse angular lumps, of a conchoidal fracture, is trans- 
lucent on the edges, of a resinous lustre, and leek-green 
color, with red and yellow spots. It scratches white glass, 
has a specific gravity of 2*61 to 2'63. HeUotrope is 
found among amygdaloid, in Tyrol, in the United States 
(in New York, near Troy), Scottish Islands, Siberia, Faroe 
Islands, Egypt, Barbary, Tartary, &c. It is principally 
employed in rings and seals, watch-keys, snufi'-boxes, and 
other articles of jewelry, — also for sword and dagger han- 
dles ; and is wrought like chalcedony, but sometimes cut 
on brass plateif; its forms are various: as cabochon and 
pavilion. 



AGATE. 283 

Heliotrope has been greatly admired in modern times ; 
its price depends upon the color and quantity of red spots 
contained in it. From one to twenty dollars is the usual 
price for good and large specimens. 

It is said that superstitious people in the middle ages 
valued the heliotrope, with many red spots, very highly, 
thinking that Christ's blood was diffused through the stone. 

AGATE. 

This stone was well known to the ancients, under the 
name of achates, and was used for various purposes of 
jewelry. In Rome, it was principally used for cutting 
cameos from the striped kind, the onyx. It has also been 
worn as an amulet, with different characters engraved on 
it. Its name is derived from a river in Sicily, where the 
ancients procured it. Agate is a mixture of several species 
of quartz, which are variously combined ; chalcedony or 
carnelian usually forms the principal part, and is mixed 
with hornstone, jasper, amethyst, quartz, heliotrope, ca- 
chelong, and flint; and according to the predominating 
substances, it is sometimes called chalcedony, jasper, or 
carnelian agate. Its color, as well as its other characters, 
depends upon the nature of the mixed parts ; likewise its 
hardness ; but it usually scratches white glass, and has a 
specific gravity of 2*58 to 2*66 at the utmost. 

According to the different figures represented in agate, it 
receives its various names. 

1st. Ribbon, or striped agate, representing layers vari- 
ously colored, and alternating with one another. Onyx^ 
or agate onyx, are such agates as.have the colors beautiful 
and distinct, and whose layers run in a parallel direction 
with the larger surface ; whereas the common ribbon agates 
display their various layers on the surface, without being 



284 A POPULAR TREATISE ON GEMS. 

parallel. If the stripes run together around the centre, it 
is called the circle agate, and if in the same stone the 
centre shows more colored spots, it is called the eye agate, 
or eyestone. 

2d. Fortification agate is that brownish agate, the vari- 
ous colored stripes of w^hich run in a zig-zag, or irregular 
lines and angles, representing the ground plan of fortifica- 
tions. 

3d. Rainbow agate ; the curved stripes have the prop- 
erty of displaying rainbow colors when held towards the 
sun, or candle-light, and the more distinctly if the stone is 
cut very thin. 

4th. The cloud, landscape, dendritic, figure, moss, punc- 
tated, star, petrifaction, shell, coral, tube, fragment, and ruin 
aQ:ates are all the various forms in which the ao^ate is dis- 
played, according to its figure or drawing. A ruin or frag- 
ment agate may be pasted together from the fragments ot 
a common ribbon agate, so as to make it represent old 
walls, whereby it receives the name of breccia agate ; some- 
times the rainbow a'srate occurs in connection with the shell 
agate, where the moss surrounding the petrified shells forms 
the rainbow-agate. 

The royal collection at Dresden contains a table service 
of German agate ; at Vienna, in the imperial cabinet, there 
is an oval dish twenty-two inches in length, formed from a 
single stone. ' 

The achates of the Greeks was so called from the river 
Achates, in Sicily, whence, according to Theophrastus, 
these stones were originally brought. 

Jaspachates corresponds to our jasper-agate ; sardachates 
contained layers of the earda, or carnelian ; dendrachtes, 
from devdpov^ a tree, corresponding to our moss-agate ; 
hsemachates, from aciia^ blood, which w^as an agate sprinkled 
with spots of red jasper. 



AGATE. 285 

Among the crown-jeAvels of France is a very valuable 
set of agates, — ten cups and saucers, four urns, four chan- 
deliers, four busts, two ewers, two basins, two vases, two 
bowls, two salvers, one decanter, and one candlestick ; the 
whole set is valued at 500,000 francs. 

At the French Exhibition in 1855, a magnificent Oriental 
agate, by Froment Maurice, belonging to the Princess 
Mathilde, was exhibited, having the engravings of the 
three infatuations, — the amorous, poetical, and sad, most 
tastefully represented. It is the Benvenuto Cellini of our 
day. 

The most celebrated cameo in Oriental agate, is the 
bust of Alexander the Great, which is a perfect gem ; the 
head is quite independent in color from the base of the 
stone, and the execution without a blemish. 

The Orleans collection contained two agates : one repre- 
senting the death of Cleopatra, as a half-body ; the other, 
Lysimachus, the head girdled with a diadem. 

A large black agate, particularly remarkable for its per- 
fection and the complication of its Workmanship, repre- 
sented a captive followed by two generals on horseback, 
and several other persons, one shoAving a trophy, and an- 
other a laurel branch. 

An intaglio of Neptune, belonging to the Sabatini Mu- 
seum, was also exhibited. 

Agate is found in gangues, in gneiss, porphyry, or amyg- 
daloid ; also, as boulders and pebbles, in rivers, &g. It 
is found in Baden, Oberstein, Saxony, Bohemia, Hungary, 
the Faroe Islands, Siberia, the West Indies, and in the 
United States (Massachusetts, Rhode Island, New Jersey, 
Indiana, Missouri, Maryland, Georgia). Those occurring in 
amygdaloid are mostly in the form of geodes or balls, 
hollow inside, and coated with quartz or amethyst ; when 
the rock begins to disintegrate, these balls, becoming 



286 A POPULAR TREATISE ON GEMS. 

loose, fall scattering around the soil, and are then collected 
by persons who make a business of either selling or cutting 
them. 

The agate is used, not only for various purposes of 
jewelry and ornaments, such as seals, snuff-boxes, crosses, 
cases of various descriptions, ear-drops, &c., but also for 
numerous other useful purposes, on a large scale ; such as 
slabs, mortars, vases, instruments, knife and fork handles, 
playballs, &c. The manufacturing of them forms a con- 
siderable branch of industry in a part of Germany. The 
agate, after having been reduced to suitable sized pieces, 
by means of a saw, chisel, or hammer, is then cut on a 
copper Avheel, by means of emery, powdered garnet or 
topaz, and is afterwards polished on a tin plate, with rotten- 
stone, putty, or pumice-stone. 

Oberstein, a small place in Rhenish Bavaria, in the north 
of Germany, has five large manufacturing establishments 
for the sole purpose of cutting and polishing the common 
gems or semi-precious stones, and it is the only place where 
this branch of business is carried to any great extent. 
Twenty mills are constantly driven by water, and more 
than one hundred thousand dollars' worth of work is turned 
out yearly for export ; a sum which is small in comparison 
with the enormous quantity of goods manufactured and set 
afloat, but pretty considerable for such places, where labor 
is so cheap, and the best of workmen may be had for one 
dollar and fifty cents per week. At Oberstein the business 
is divided into two branches : the one is devoted to the 
cutting and polishing of the agate, and the other to the 
boring ; the workmen are called agate lapidaries and 
agate borers. The cutting is performed in the large 
agate mills, on sandstone ; each mill has generally five 
large sandstones, five feet in diameter and fourteen to 
fifteen inches in thickness, fastened upon a shaft, which 



AGATE.. 28Y 

causes them to revolve vertically, and which are continually 
moistened by a stream of water. The workman leans with 
his body upon a peculiar bench, the seat of which is called 
the cuirass, and with his feet presses himself against a pole, 
whence he continually pushes the larger lumps of the agate 
towards the mill-stone; this, however, is often made so 
smooth, from the friction, that it is often necessary to make 
it rough by knocking it with a sharp hammer, according to 
the kind of work, whether fine or coarse. The stones are 
either polished on sandstone or on wood, by means of fine 
clay or powdered chalk ; they are polished sometimes, also, 
on wooden wheels, covered with lead or tin. Snufilboxes 
and other articles of agate, which are hollow, are polished 
on smaller sandstone wheels, which diminish in size as the 
work advances. Agates which require to be bored belong 
to a particular branch, distinct from the other. The boring 
is performed by means of a diamond point, and as described 
by Mr. Mawe. The onyx varieties are mostly employed 
for cutting canleos, and are prepared there in* such a man- 
ner that the darker layer is cut for the base, and the lighter 
'for the intended objects. 

There is in Siberia, at Katherineburgh, an extensive 
manufactory for grinding and polishing agate and other 
gems. 

Many varieties of agate are used for engraving other 
stones, and also for the Florentine or stone mosaic work. 
Since agate has always been, and is yet, a favorite stone, 
it has been attempted to improve either its color or other 
external appearance by artificial or mechanical means ; this 
is done either by the use of metallic solutions or by boiling 
in oil of vitriol. The color has often been improved by 
giving to the stone, before it is polished, several strokes in 
succession, the small fissures thereby produced displaying 
an iridescence or some other phenomenon, if held towards 



288 A POPULAR TREATISE ON GEMS. 

the light ; this operation, however, may easily be detected 
by wetting the stone, when the water, entering the fis- 
sures, will destroy the effect ; it will show itself again when 
dry. On some agates black and white layers are produced, 
in order to use or sell them in the place of real onyx ; this 
operation is performed by the lapidaries, who boil certain 
varieties in oil of vitriol, which changes the color of some 
very soon to black, and renders others clear or stiU paler ; 
only polished agates are used for this purpose, and the 
cause appears to lie in the oil absorbed by them during, the 
operation of polishing, on which account agates are by some 
first boiled in oil before submitting them to the, operation of 
the oil of vitriol. 

The value of agate, although much reduced, in com- 
parison to former days, — a great deal depending upon 
the purity and perfection of color and peculiar figures, — 
commands a pretty good price in the market ; it is particu- 
larly the onyx which is yet at high prices, and on that 
account it ii imitated by pasting thin plates of chalce- 
dony, jasper, agate, &c., together, and making them, by 
{heir different colors, appear like real onyx ; this deception 
may, however, be easily detected by jDutting it into hot 
water, which disengages the plates one from another ; the 
onyx is likewise imitated by pastes, a'hd very happily, but 
may readily be distinguished from them by the hardness 
and other characters prominent in the real stones. 

Onyx, which, as already stated, is a variety of agate, 
and most frequently of chalcedony, possesses in its in- 
trinsic characters a regular alternation of layers, which are 
more or less thick, and of distinct different colors, usually 
the grayish white, brown, and black predominating ; while 
sardonyx indicates one layer or more to be of carne- 
lian, and this is in higher estimation. It was this stone par- 
ticularly which the ancients mostly sought after for engrav- 



I 



AGATE. 289 

ing the heads of celebrated persons, their deities, and their 
idols; the fawn-colored variety, which is neither yellow 
nor red, was the highest in value. Both onyx and sar- 
donyx were purchased in Arabia and the Indies, and the 
harder the stones and finer the grain, the more valuable 
they were for the purpose of cutting. The title of Oriental 
onyx was always given to the finest qualities of the 
stones, regardless of the locality from whence they were 
brought. 

The Imperial Library at Paris possesses some of the most 
antique cameos and intaglios of onyx, such as Germani- 
cus, Marcus Aurelius, Faustina,^ and Tiberius ; the dread- 
ful Jupiter is an onyx in two layers ; Venus on a marine 
bull, surrounded by cupids, are personifications of the 
highest perfection in the art. 

The superb fragment existing in Rome, and representing 
Antilochus announcing to Achilles the death of Patrocles, is 
another master-piece ; the cameo has a black ground, with 
a white layer above, and the expression of grief on the 
three faces has secured to this cameo the decided suprem-,, 
acy of the ancient over the modern art. 

The bowl of Capo di Monte, in the Royal Museum of 
Kaples, and the great cameo of Alexander and Olympia, 
belong to Mr. Bracciano, at Naples. 

The French Museum contained the great cameo of An- 
touius and Faustina, engraved in different colors, but not 
parallel lines, it is not inferior to any other : the ground, 
which is of agate of brownish color, is Antonins, and 
above, in a white layer, is the pleasant figure of Faus- 
tina, whose drapery and hair ornaments are exceedingly 
well executed in a lilac color. 

The sardonyx is also called sarde, and if of a dark sable 
color, was preferred by the ancients for cutting intaglios. 

Mars and Venus when surprised by the gods, is executed 

13 



290 A POPULAR TREATISE ON GEMS. 

by Valeric Yicentine; it represented nine figures. The 
Nuptials of Cupid and Psyche contains five figures. 

In the inventory of curiosities belonging to the crown of 
Franxje, made in 1791, are mentioned two vases of sardonyx, 
valued at sixty-four thousand francs ; six sets, at one 
hundred and sixty-seven thousand francs ; two cups at six- 
teen hundred francs; one decanter at thirteen hundred 
francs ; one urn at six hundred francs ; but one remarkable 
sardonyx, of a grayish yellow mixed with brown, on which 
a Medusa head was engraved, was valued at twelve thou- 
sand francs. 

The onlcolo or nicolo is another variety of onyx; it is 
of brown ground with a band of bluish white ; it is distin- 
guished from onyx, by the lower layer being always thin- 
ner than the upper ; it is not so highly valued as either the 
onyx or sardonyx. The Mineralogical Cabinet at Paris 
possesses several cameos of this material ; one represents 
military piety ; also a cameo of Adonis, by Coinus. The 
stone is probably the mgyptilla^ described by Pliny. 

The real sardonyx is the rarest mineral among that class 
of stones, on account of the multiplicity of layers, of which 
there are as many as ten, all, however, from the same sub- 
stances, but diiferently colored : such as chalcedony, jasper, 
agate, white, gray, red, and bi'own, opaque, translucent, 
bluish, or yellowish ; they are highly prized, particularly 
those from the Orient. 

The finest cameo of the real Oriental sardgnyx is in the 
imperial cabinet of Vienna, it is said to come from Diosco- 
rides ; it was obtained by Rudolph II., the German emperor, 
for 12,000 ducats. 

In the crown-jewels of France are some unique cameos 
of sardonyx, such as the triumph of Bacchus and Ariadne, 
valued at 7000 francs, and eleven other cut stones valued 
together at 60,000 francs. 



AGATE. 291 

Great collections of antique onyxes; engraved as cameos 
and intaglios, are in Vienna and Berlin ; in the first is to 
be seen the apotheosis of Augustus, which is ten lines broad 
and six high, and contains twenty perfect figures ; this was 
purchased by the Emperor Rudolph at Frankfort-on-the- 
Maine, for fifteen thousand ducats. 

The celebrated cameo in the Vatican Museum, at Rome, 
is of agate, and represents Augustus. Italy has always been 
the great emporium for genuine antique onyxes and cameos, 
and occasionally we still behold fine specimens of art in the 
possession of travellers coming from Europe. A very fine 
collection of antique cameos and intaglios in precious gems 
and antique pastes, likewise cameos and intaglios of modern 
artists, I have seen in this country, in the possession of 
Thomas G. Clemson, Esq., of Philadelphia. 

I have in my collection a good onyx of the Emperor Vi- 
tellius ; a splendid cameo of Bacchus, of two and one fourth 
inches long and one half inch thick ; one of Antony and 
Cleopatra ; also a splendid intagUo. 

In Paris are several celebrated cameos, worthy the notice 
of travellers going to Europe : the Brunswick Vase was cut 
from a single stone, and has the form of a cream pot, about 
scA^en inches high and two and a half broad on its outside, 
which is of a brown color; there are white and yellow 
groups of raised figures, representing Ceres and Triptole- 
mus in search of Proserpine ; AgrijDpina and her two chil- 
dren, composed of two layers, brown and white ; the Quar- 
rel of Mmerva with Neptune, which consists of three layers ; 
Venus on a sea-horse, surrounded with cupids, &g. 

The Museo Borbonico at Naples contains an onyx meas- 
uring eleven inches by nine — the apotheosis of Ptolemy on 
one side, and the head of Medusa on the other ; both are 
splendid specimens of art, and supposed to be the largest in 
existence. 



292 A POPULAR TREATISE OX GEMS. 

Two very beautiful flower-vases of black onyx, colored 
with natural white veins, two large cups of red chalcedony 
colored, long square links of chalcedony, connected together 
without joints, and alternating in colors, also a very beau- 
tiful snuif-box of green jasper, were seen at the London 
Exliibition, manufactured by Wild & Robinson, in Oberstein. 

Some modern works of cam6o, from the hand of the cele- 
brated Puckler, are in the collection of Robert Gilmore, 
Esq., at Baltimore, and in that of W. J. Lane, Esq., of this 
city, who possesses also a Washington head of black and 
white onyx, by Isler, which is extremely beautiful ; also a 
very fine modern cameo in onyx, two inches in length, I 
saw in Stephen H. Palmer's establishment. 

CHRYSOPRASE. 

The ancients by this name designated a stone of a green 
color, with a yellowish tinge; but it is not certain whether 
that which goes by this name, at the present day, is the 
same. We find, in the fourteenth century, this stone used 
as ornaments in churches and other places, but it was not 
known by the above name until 1740, when it w^as discov- 
ered by a Prussian officer in Silesia. Frederick the Second 
ornamented his palace Sans Souci with this mineral. 

The common people of Silesia wear the chrysoprase 
around the neck as a charm against pains. 

Chrysoprase occurs massive and in plates ; the fracture 
is even and splintery ; it is translucent ; lustre, resinous ; 
sometimes dull apple-green, grass-green, olive-green, and 
whitish-green color ; it scratches white glass distinctly, but 
is not so hard as true chalcedony; specific gravity, 2*56; 
it is infusible before the blowpipe, but loses its color when 
heated ; it consists of silex, with a little carbonate of lime, 
alumina, oxide of iron, and nickel ; its color is imparted by 



CHRYSOPEASE. 293 

the latter substance. This mineral is found in the serpen- 
tine of Silesia ; also, in Siberia, and in the United States 
(in New Hampshire). 

Chrysoprase is used in jewelry and for various ornamental 
purposes, such as breastpins, rings, bracelets, necklaces, 
seals, &G. ; and the larger masses are used for snuff-boxes, 
cane-heads, table-plates, &c. The cutting is pretty difficult, 
and the greatest care is required for finishing the same 
with facets, as it is easily fissured ; it is done on tin or lead 
plates with emery, keeping the first constantly wet with 
water ; it is polished on a tin plate with rotten-stone, but 
the lapidary has always to be cautious not to let it become 
hot, as it easily splinters, and grows opaque and gray. 
The usual cut is the table or cabochon, with facets on the 
border ; in setting, a foil of green satin is often us-ed for a 
back, but when pure and of good color, it is mounted djour. 
Inferior specimens are painted on the back with a mixture 
of verdigris, white lead, and gum mastic, or with sap-green. 

The chrysoprase loses its color by wearing; heat and 
sunlight likewise cause it to fade, and render it dark and 
cloudy ; but the color may be restored by keej^ing it in a 
wet or moist place, such as a cellar, in wet cotton or sponge, 
or even by dipping it in a solution of nitrate of nickel, 
which serves likewise to improve the inferior qualities. 

Very fine imitations in paste may be made by mixing 

1 000 parts of strass with 

5 " of oxide of iron, and 
8 " of oxide of nickel. 

The chrysoprase is subject to a great many faults, such 
as fissures, either natural or received in cutting ; oily whitish 
spots, pale gray flaws and stripes, and sometimes small 
grains of clay of reddish color, intermixed in the interior of 
the stone ; but when pure, the chrysoprase has always been 



294 



A POPULAR TREATISE ON GEMS. 



a great favorite. A good seal or ring stone may be worth 
from twenty-five to thirty dollars, and smaller specimens 
from one to five dollars. The apple-green variety is most 
valued, and a specimen one line long by one half broad, 
has been sold at from fifty to one hundred and fifty dollars. 
At Paris, an oval chrysoprase, eight lines long and seven lines 
broad, was sold for three hundred and ten francs. The 
price generally has decreased of late, on account of the 
great quantity cut from the mines, which have recently 
been covered up, in order to raise its value again. At the 
royal palace of Potsdam, in Prussia, are two tables of chrys- 
oprase, the plates of which are three feet long, two feet 
broad, and two inches thick. 



CHRYSOLITE, PERIDOT, OLIVIN. 

The name of this stone is of Greek origin, and was well 
known to the ancients, although it is undecided whether 
they designated the same mineral by this name that we do 
at the present time, for they make it in their writings to be 
either the topaz or goldstone, or the transparent gold- 
yellow stone. 

The chrysolite occurs in prismatic forms, generally a 
right prism with rectangular bases; also, in angular 
rounded crystalline grains or massive ; 
the fracture is conchoidal ; it is trans- 
parent and translucent ; it possesses 
powerful double-refracting power ; its 
lustre is vitreous and resinous; the 
lateral planes of the crystals are some- 
times striated ; the color is olive-green, 
turning to yellowish and brownish ; 
it scratches glass indistinctly, and is 
attacked by topaz ; hardness, 6*5 ; 




Fig. 10. 



CHRYSOLITE. 295 

specific gravity, 3"33 to 3*44 ; becomes electric by rubbing; 
is infusible by itself before the blowpipe, but is dissolved 
into a transparent pale-green bead with borax; acids do 
not affect it ; it consists of magnesia, silica, and oxide of 
iron. Chrysolite is found particularly in basalt, trap, green- 
stone, porphyry, and hwa ; sometimes in alluvial deposits 
and the sands of rivers. 

The perfectly crystallized chrysolite is brought from 
Constantinople, but its true locality is unknown ; less dis- 
tinct crystallizations occur imbedded in lava at Vesuvius 
and the Isle of Bourbon ; imbedded in obsidian at Reel del 
Monte, in Mexico ; among sand at Expaillie, in Auvergne, 
in pale-green transparent crystals. 

Egypt, Natolia, and Brazil are the principal localities 
for the prismatic chrysohte ; the olivin is more frequently 
found in imbedded crystals and granular aggregations, in 
the basalts of the Habichtswald, the Eiffel, the Upper 
Palatinate, Geysingburg near Altenburg, Kapfenstein in 
Styria, and in the sienite at Elfaden in Sweden. The brown 
variety (hyalosiderite) is found at Sabbach and Iringen on 
the Kaiserstahl, and in dolorite, near Freiburg in Baden. 
Crystals of olivin, several inches in length, occur in green; 
stone, at XJnkle near Bonn, on the Rhine, and it is a fre- 
quent ingredient of meteoric stones. 

The word chrysolite is derived from ;\;pi^<To^, gold, and 
Xl6o^, stone, in allusion to its color. 

The dark-colored peridots, which take a high polish, are 
now much worn in Europe ; they lose, however, their gloss 
very soon, on account of their softening. 

The Hgurite is a species of chrysolite of an apple-green 
color, is transparent and of uneven fracture; hardness, 5*3; 
specific gravity, 3'49. Its primary form is an oblique 
rhombic prism ; the ligurite contains some alumina and 
lime in addition to the composition of the chrysolite ; it is 



296 A POPULAR TREATISE ON GEMS. 

considered a superior gem to chrysolite, both in color and 
transparency. It occurs iu a talcose rock on the banks of 
the Stura, in the Apennines of Liguria ; it does not become 
electric by heat or friction. 

The bottlestone of Moravia is likewise a species of chrys- 
olite, of dirty-green and grayish-green colors, does not 
occur crystallized, but in flat pieces of about an inch in size ; 
some specimens which the author collected in his youth, in 
Moravia, were fair specimens suitable for cutting, their 
color being dark-green. 

The chrysolite is cut on a leaden w^heel with emery, and 
is polished on a tin plate with rotten-stone or oil of vitriol. 
Sometimes pale stones are finally polished .with some olive 
oil, which raises the color considerably : this last operation 
is applied to restore its lustre, after the chrysolite becomes 
dull by wearing. The form is that of a rose or table cut ; 
also in pavilion ; and when set, gold foil is used for its base : 
the pale-colored chrysolite looks well with a green-colored 
copper foil ; dark chrysolites may be rendered clearer by a 
careful calcination. 

The chrysoUte is used for rings and pins, but does not 
stand in high estimation, not possessing either a distin- 
guished color, strong lustre, or great hardness, and losing 
its jDolish by wearing ; on account of its softness, it wears 
off" at the edges. Very good specimens of peridot from 
Brazil were brought into this country from France, and 
commanded a good price, a few years ago, viz : fi'om ten 
to fifteen dollars a carat. 

Chrysolite was much esteemed by the ancients ; Queen 
Berenice received a chrysolite as a present from Phile- 
mon, lieutenant of King Ptolomeus. 

Cleopatra likewise gave one to Antony. Louis XIII. 
brought chrysolite into fashion at his court. 

Among the engravings in chrysolite is one of the Em- 



i 



lOLITE. 



297 



peress Sabine, which is in the cabinet of Crispi, at Ferrara, 
Among the most extraordinary engravings in chrysolite, 
is one representing Ptolomeus-Oulet, king of Egypt, and 
the Nuptials of Cupid. 



lOLITE. 

This mineral has for a long time been brought from 
Spain, but has lately been made known and brought into 
notice by Cordier, after whom it received the name cor- 
dierite ; it is called likewise steinheilite, and has several 
other names, Which I will mention, in order that the reader 
may not be confused when the same mineral is presented 
as a gem," under different names; the most appropriate 
name is cUchroite^ from its property of displaying two 
colors when held in different directions ; it is also known 
as peliom and prismatic quartz. 

It occurs in regular six and twelve sided prisms ; also, in 
crystalline grains, massive, and in pebbles ; its fracture is 
conchoidal and uneven ; it is transparent, 
exhibiting an indigo-blue color when held 
in the direction of its axis, or idewed by 
transmitted light, and appearing brown- 
ish-yellow when held at right angles ; it 
possesses some double-refracting j)ower. 
Sometimes a ray of light, resembling that 
of the star-sapphire, may be perceived in 
iolite, particularly when cut; it has a 
vitreous lustre ; its colors are violet-blue 
and indigo-blue, sometimes with a tinge 
of black and bluish-gray. It scratches glass, and is attacked 
by topaz ; its 'streak-]3owder is white ; hardness, 6*5 ; it 
has a specific gravity of 2*88. By rubbing, it becomes 
electric, and assumes polarity by heating ; it is difficult to 

13« 




Fig. 11. 



298 A POPULAR TREATISE ON GEMS. 

fuse on the edges, and becomes then a grayish-green 
enamel : borax fuses it into a diaphanous glass ; acids have 
no effect upon it ; it consists of magnesia, alumina, and 
silica, with some oxide of iron and water. 

It is often found under the names of lynx and water 
sapphire, the first of a pale and the latter of a darkish blue 
color. It is found in primitive rocks ; also, in blue clay, 
in copper pyrites, in quartz or felspar, and in small de- 
tached masses ; the localities are at Baldenmays in Bavaria, 
occasionally in perfect crystallizations, but usually massive ; 
it is associated with magnetic pyrites. The variety from 
this locality has been called peliom, from its peculiar smoky- 
blue color, from ireXiog. It occurs in quartz, at Ujordlero- 
soak, in Greenland ; in granite, at Cape de Gata, in Spain ; 
at Arendal, in Norway ; at Orrijervi, in Finland ; at Tuna- 
berg, in Sweden, &g. Ceylon affords a transparent variety 
in small rolled masses of an intense blue color. At Had- 
dara, Connecticut, it is associated wdth garnet and anthoph- 
yllite in gneiss. It is occasionally employed as a gem, 
and when cut exhibits its dichroism, or different colors in 
different directions. The name iolite is derived from tov, 
a violet, and Xtdog^ stone, in allusion to its color. From its 
property of exhibiting different colors according to the 
direction in which it was viewed, it has also been named 
dichroite, from dig, double, and XP^^^ color. 

The hydrous iolite, from Sweden, of grayish-brown or 
dark olive-green color, is a very soft mineral ; hardness, 
S'VS ; occurs in red granite, accompanied by a light bluish- 
gray iolite. 

■ If the stone is perfectly pure, it is used for rings and 
breastpins; is cut on a copper wiieel with emery, and 
polished on a tin plate Avith rotten-stone, and receives the 
form of a cabochon, in order to let it display its proper 
colors, and in a cube form. Its price is not very high ; the 



PEECIOUS OPAL. 299 

jewellers value it as an inferior quality of the saj^phire, 
without paying any regard to its phenomena of light. 
Good-sized specimens are sold at about eight to ten dollars 
each ; at Paris, a good iolite, ten lines long and eight and 
a half broad, was sold for one hundred and sixty francs. 
When, a couple of years ago, the iolite was discovered by 
Professor Mather, at Haddam, Connecticut, it promised to 
be a valuable acquisition to American gems ; but the 
supply was very scant, and its original locality appears to 
be exhausted. Professor Torrey possesses a fine seal, in 
the form of a cube, from that locality, which displays its 
properties to the greatest perfection. 

A blue quartz is occasionally sold for iolite, but it may 
easily be distinguished by its colors and hardness. Sapphire 
is considerably harder than the iolite. 

OPAL. 

The precious variety of this mineral was known to the 
ancients, and receiyed its name on account of the play of 
colors which if has. The opal has a great many varieties, 
which are all considered more or less gems, and find their 
ap]3lication in jewelry; they will therefore be treated 
separately. But, as general characters, it may now be men- 
tioned that opal scratches glass but shghtly, while it is 
marked by rock-crystal ; it has a specific gravity of 2*06 to 
2*11 ; it is infusible before the blowpipe, but decrepitates 
and falls into splinters ; it also dissolves with borax. Opal 
consists of silica with water, some oxide of iron, and some- 
times alumina. 

PRECIOUS OPAL. 

This gem derives its name from the Greek word sig- 
nifying the eye, for the ancients beheved that this stone 



300 A POrULAH TliEATISE ON GEMS. 

had the power of strengthening the eye. It was highly 
esteemed by them, as we learn from Pliny, who thought 
that the play of color originates from the beautiful colors 
of the carbuncle, amethyst, and emerald. 

The phenomenon of the play of colors in the precious 
opal has not yet been satisfactorily explained. Hatiy attrib- 
utes it to the fissures of the interior being filled with films 
of air, agi'eeably with the law of Newton's colored rings, 
Avhen two pieces of glass are pressed together. Mohs con- 
tradicts this theory upon reasonable grounds, which are, that 
the phenomenon would present merely a kind of irides- 
cence. Brewster concludes that it is owing to fissures and 
cracks in the interior of the mass, not accidental but of 
a uniform shape, and which reflect the tints of Kewtpn's 
scale ; but it is, in my opinion, sufficiently plausible, that 
the unequal division of smaller and larger cavities, which 
are filled with water, produces the prismatic colors, and for 
the simple reason that the opal which grows, after a while, 
dull and opaque, may be restored to its former beauty if 
put for a short time in water or oil. 

Although the precious opal was never fovftid in the East, 
yet it bears the name of Oriental opal among jewellei's : 
for in former times opals were carried by the Grecian and 
Turkish merchants from Hungary, their native locality, 
to the Indies, and brought back by the way of Holland 
to Europe, as Oriental opals. The precious opal is found, 
in small irregular gangues, nests of the trachytic por- 
jjhyry formation and its conglomerates, in Hungary, par- 
ticularly in the neighborhood of the village of Czerwin- 
ceza ; also, in the Faroe Islands, Saxony, and South America. 
The Hungarian opal is found of various qualities, and is 
obtained from mines which have been wrought for several 
centuries; and, according to the archives of that part of 
the country, there were, in the year 1400, more than three 



PEECIOUS OPAL. 301 

hundred workmen engaged at the mines near the above 
village ; whereas there are but thirty at present engaged 
there, on account of the scarcity of large suitable speci- 
mens. 

The precious opal is principally used for rings, ear-rings, 
necklaces, and diadems ; the smaller specimens for mount- 
ing snuiF-boxes, rings, chains, &g. It is ground on a leaden 
wheel with emery, and is polished with rotten-stone and 
water on a wooden wheel ; and, in order to increase its 
lustre, it is lastly rubbed with putty, by means of buckskin, 
or a woollen rag and red chalk. Its form is generally that 
of a semicircle, lens, or oval; sometimes of a table, and 
then also with some facets ; but great care has to be taken 
that the edges, on account of the softness of the stone, do 
• not wear off. It is also apt to spring in a temperature sud- 
denly changing. When mounted, it receives a colored 
foil, or a variegated, silk stuff, or a peacock-feather on the 
back, but it looks best in a black casing. 

Cracks and fissures may be removed by leaving the pre- 
cious opal for some time in oil. Very frequently the pre- 
cious opal is distributed in small particles in the matrix, 
called mother of opal, which is cut by the jcAvellers as 
boxes, and other ornaments ; and very often, too, this 
matrix is plunged into oil, and exposed to a moderate heat, 
whereby the base grows blacker, and the true precious 
opal retains its ray of colors. In order to preserve the 
surface of the precious opal against wear and tear, it is 
covered with a thin plate of quartz crystal. The precious 
opal still stands in very high estimation, and is considered 
one of the most valuable gems. The size and the beauty 
displayed by its colors determine its value ; those playing 
in the red and green colors bear the highest price. Its 
value has latterly increased on account of the scarcity of 
the larger specimens. Formerly, a sohtary large precious 



302 A POPULAK TREATISE ON GEMS. 

opal, playing in the red color, was sold for two to three 
hundred ducats ; and one playing in both red and green 
colors, about five lines long, was sold at Paris for two 
thousand four hundred francs ; and lately a single opal, of 
fine colors, and the size of a dollar, was sold near the 
locality for three hundred thousand florins ; in this country 
precious oj^als are sold by the importers at the rate of 
four to ten dollars per carat, and single specimens, suitable 
for pins or rings, from two to twenty dollars. The mother 
of opal is, however, much cheaper ; one of five lines size is 
sold for three to five dollars. 

All experiments for imitating the precious opal have 
hitherto proved fruitless ; they were made either by pre- 
paring an enamel and adding several metallic oxides, or by 
afiixing to the back of a clear or common opal or enamel, a 
polished thin plate of the mother of pearl, which may some- 
times deceive the ignorant. 

The precious opal, when large and exhibiting its peculiar 
play of colors in perfection, is a gem of considerable value ; 
it was used as an ornament among the Greeks and Romans, 
and was called opalus ; also ^^aecZeros (iraidepcjc;) ^ in allusion 
to its .color and lustre as expressed in the Orphic poem : 
" Ifieprov repeva xpda Traiddg, — having the delicate com- 
jDlexion of a lovely youth." The most magnificent Hunga- 
rian opal in the London Exhibition, called '' the mountain 
of light" — a very approi^riate name — weighed 526 ^ carats, 
and was estimated at 4000 pounds sterling. 

From Honduras, at Gracias a Dios, large quantities of 
opals have been imported into this city for the last ten years, 
at first by the late Mr. De la Raye, and latterly by Mr. 
Aaron C. Burr ; and many large and beautifully cut speci- 
mens are in the possession of Mr. B. Palmer, of this city ; 
they are by no means inferior to the Hungarian opal. A 
very large opal, cut and pohshed by himself, which he 



PRECIOUS OPAi. 303 

values at four thousand dollars, is one and three quarters 
inches long by one. and a quarter inches wide; another, 
" one and a quarter inches long by one inch wide, he prizes 
at seven hundred and fifty dollars ; and a third, one and 
one eighth inches long by one inch wide, he values at four 
hundred and fifty dollars. 

The ancients held the opal in great estimation, and the 
anecdote of the Roman senator, ISTonius, is well known — 
that he preferred exile to parting with a magnificent opal 
which Marc Antony coveted. 

In the French crown-jewels are two very large and 
beautiful opals. One is set in the centre of the Order of 
the Golden Fleece, and the other forms the clasp of the 
imperial cloak. They were purchased for 75,000 francs. 
The Empress Josephine possessed the unique opal which 
was called " The Great Fire of Troy," on account of the 
great fire sparkles. 

The Vienna Cabinet possesses a very large opal, but 
unfortunately it is cracked. Count Walewski, who is a 
great amateur of gems, possesses a very beautiful opal, 
which is oval, the size of a franc-piece, and is said to be 
extraordinarily brilliant. 

The Imperial Mineralogical Cabinet at Vienna, contains 
the most celebrated specimens of precious opal ; one, par- 
ticularly, may be mentioned here : it is four and three 
quarter inches long, two and a half inches thick, and weighs 
seventeen ounces. It was discovered about 1770, at the 
above locality, and transported to Vienna. It displays the 
most magnificent colors; is perfectly pure, and not accom- 
panied by any matrix. Half a million of florins were 
offered for it by a jeweller of Amsterdam, and refused on 
account of its uniqueness ; and the Viennese have not yet 
dared to put even any approximate value upon it. 



304 A POPULAR TREATISE ON GEMS. 



FIRE OPAL. 

This mineral was first brought mto notice by Baron 
Humboldt, who found it in Mexico. 

It occurs massive ; has a conchoidal fracture ; is trans- 
}>arent ; of strong vitreous lustre ; color, hyacinth-red, run- 
ning into honey, Avine-yellow, showing carmine-red and 
greenish reflections ; sometimes containing dendritic draw- 
ings. Its specific gravity is 2*02 ; loses one and a half per 
cent, by calcination, and leaves pale flesh-red fragments. It 
is found in the trachytic porphyry, in Mexico, and in the 
amygdaloid of the Faroe Islands. 

As the fire opal is very little known, it has not yet 
been employed in jewelry, but bids fair to find applica- 
tions. It is ground on a leaden wheel with emery, and 
polished with rotten-stone on a wooden wheel. The forms 
of cabochon, table, or pavilion, might suit very well as ring- 
stones. 

The cabinet of the university of Bonn possesses a very 
large and fine fire opal, of the size of the fist. The largest 
specimen I have seen is in the royal mineralogical cabinet 
at Berlin, which was deposited by Baron Humboldt on 
his return from South America, and which, if I recollect it 
well enough from the year 1827, must be at least six inches 
long and four inches thick. This is the largest specimen 
he ever found. A collection of six shades of fire opal, with 
six more varieties of the other opals, was presented to me 
in the year 1828, when in Berlin, by the Counsellor Berge- 
man, who received at that time a considerable quantity of 
polished specimens from the Faroe Islands, but all of small 
size. A splendid collection of fire opals was brought from 
Guatemala some years ago to this country. It is also called 
girasol, from its bright hyacinth-red tints. 



HYDKOPHANE. * 305 



COMMON^ OPAL. 



This mineral occurs massive and in rolled pieces ; also as 
stalactites ; has a conchoidal fracture ; is translucent and 
semi-transparent ; has a strong vitreous and resinous lustre ; 
its colors are milky, yellow, reddish, greenish-white, honey- 
yeUow, wine-yellow, flesh, brick-red, and olive-green ; some- 
times dendritic (moss opal). Its specific gravity is 1*9 to 2*1 . 

The wax or pitch opal is subordinate to this variety. 
It is found in the same rocks as the precious opal, in Hun- 
gary ; in the hematite rocks of Saxony ; in the serpentine 
of Silesia ; in cavities of trap and the amygdaloid rocks of 
Iceland ; Faroe Islands ; and in the United States (Penn- 
sylvania and Connecticut). 

. It is used for rings, pms, and cane-heads ; but is, on the 
whole, not a favorite among jewellers, and has no great 
value, because it is soft and brittle ; the paste, which may 
be made from white enamel, is sometimes much prettier 
than the real stone. 

HYDEOPHANE. 

The name of this variety of opal has reference to its 
peculiar property of becoming transparent and opalescent 
after immersion in water. The ancients called this stone 
lapis mutahilis^ and achates oculus mundi. It is a common 
or precious opal, of porous texture; adheres strongly to the 
tongue ; is translucent, and absorbs water with avidity, 
giving off at the same time air-bubbles ; it thus assumes a 
high degree of transparency, and sometimes the property 
of displaying the finest prismatic colors, equal to the pre- 
cious opal. This phenomenon tends strongly to explain the 
display of the prismatic colors of the precious opal ; the 
more so, as the hydrophane loses this property on getting 
dry. 



306 A POPULAR TREATISE ON GEMS. 

It has, when dry, a white, yellowish, or reddish color, and 
a specific gravity of 1'95 to 2*01 ; and according to Hatiy, 
a hydrophane, having been immersed for four minutes in 
water, gained thirty-four centigrammes. 

The hydrophane is found in the porphyry of Hungary, 
France, Iceland, and the Faroe Islands. Large pieces of 
good and fine specimens of hydrophane are wrought and 
used in the same manner as the precious opal. 

It is said that the hydrophane becomes much quicker 
transparent in warm than in cold water ; the quickest in 
spirits of wine ; after which, it loses this property the 
sooner ; but when boiled in oil, it retains it, to a certain 
extent, for years. 

If the hydrophane is well dried and soaked in melted 
white wax, or spermaceti, it assumes the property, when 
warmed, of becoming translucent, and of disjDlaying brown- 
ish-yellow or gray colors ; it is then called pyroj^hane. 

The hydrophane was formerly colored violet or red, by 
means of a decoction of logwood and alum. 

The price of hydrophane is very high, on account of its * 
great scarcity, and because it is very seldom found in large 
lumps. 

SEMI-OPAL. 

This variety of opal was formerly considered to be a 
pitch-stone, and if it assumes the form of petrified wood, it 
is called wood opal. It has a conchoidal and even fracture ; 
it is translucent and opaque; of a resinous and vitreous 
lustre ; its colors are yellowish, grayish, and brownish, the 
colors running mostly into one another ; sometimes the 
colors divide themselves ribbon-like. The wood opal is 
mostly brownish, and displays, more or less, a ligneous 
aspect, with the form of branches. 

The semi-opal is found in gangues, in the trachytic 
/ 



CACHELONG. 307 

porphyry in Hungary, in the serpentine in Silesia, in the 
amygdaloid in Iceland and the Faroe Islands ; likewise in 
Moravia, Saxony, France, Greenland, and in the United 
States (Maryland and Pennsylvania). 

The semi-opal, on account of its taking a high polish, is 
used for many pm-poses in jewelry. There is an estab- 
lishment for manufacturing snuff-boxes from wood opal, in 
Vienna, and lately the varieties of wood opal, with layers of 
chalcedony, or semi-opal, have found a useful application for 
the cutting of cameos. The semi-opal is ground and polished 
like the precious opal, but with more difficulty, on account 
of its being more brittle. The form which it easily receives 
is in cabochon, but without facets. The price of the semi 
or wood opal is low. 

CACHELONG. 

According to Blumenb^ch, the name of this mineral is of 
Mongolian derivation, meaning " a pretty stone ;" and ac- 
cording to Phillipps it receives its name from the river Cach, 
in Bucharia, on whose shores it occurs frequently in loose 
conglomerates. This mineral has been arranged under the 
head of chalcedony, but properly belongs to opal. 

It occurs massive, as a covering of other minerals, rarely 
reniform, often traversed with fissures in different directions. 
It has a conchoidal fracture ; is opaque, and of a pearly 
lustre ; milky-white, turning sometimes to a yellow or red 
color, and exhibits dendritic figures of manganese or green 
earth. It scratches white glass ; has a specific gravity of 
2'2 ; it decrepitates when first brought before the blow- 
pipe, but yet undergoes no change ; dissolves with borax, 
slowly, at a white heat. 

It is found in the same manner as chalcedony, some- 
times incrusting or penetrating it, in the amygdaloid of 
Iceland, Greenland, the Faroe Islands, the hematite of 



308 A POPULAR TREATISE ON GEMS. 

Carinthia, the United States (Massachusetts), and Nova 
Scotia ; in Bucharia, in the sand of the river Cach, it is 
found loose. 

Cachelong being generally constituted of layers of differ- 
ent degrees of hardness, the sculptors of cameos profit 
thereby, for the purpose of producing better bas-reliefs. 

In the Imperial Library, at Paris, is a very fine cameo, 
representing Valentine III. 

Cachelong is much used in jewelry, for rings, seals, &c. 
The Calmucks of Bucharia manufacture of it tools and 
other domestic articles. It is cut on a copper wheel with 
emery, in cabochon, and receives the polish on lead plates 
by means of rotten-stone and putty. The price of the 
cachelong is pretty considerable, on account of its beauty 
and scarcity, as the specimens most frequently found in 
the above localities are seldom in layers of more than one 
quarter of a line, alternating with chalcedony. 

JASPER OPAL. 

This mineral stands between jasper and opal;, and, al- 
though considered by Werner as belonging to the first, 
ought, nevertheless, more properly to be arranged w^ith the 
opal, on account of its containing water in its composition. 

The jasper opal occurs massive, in specks, stalactiform, and 
in geodic masses; it has a conchoidal fracture; is translu- 
cent on the edges, or opaque ; is of a strong resinous lustre ; 
its colors are gray, yellow, red, and brown. Its specific 
gravity is 2'0 to 2'1. It consists of silica, water, and oxide 
of iron, amounting to forty-seven per cent. It is found in 
the trachytic breccias of Hungary; also, in Saxony and 
Siberia. The best light and pure specimens are used for 
dagger and sword handles in Turkey. The price of jasper 
opal is low. 



OBSIDIAN. 309 



OBSIDIAN'. 



This mineral was familiarly known to the ancients, and 
its name is said to be derived from a Roman, 'who first 
brought it to Rome from Ethiopia. Pliny states that the 
Romans maniifactm-ed mirrors and gems from it; the 
Mexicans and Peruvians manufactured their knives, razors, 
and sword-blades from obsidian, which appears to have 
served as a complete substitute for other materials with 
those nations, who were yet unacquainted with the use of 
iron for weapons and utensils of various kinds. Baron 
Humboldt says that Cortez mentioned, in his letter to the 
Emperor Charles V., having seen razors of obsidian at 
Tenochittan ; and the above naturalist likewise discovered, 
on the Sierra de las Nabajaz, in IS'ejv Spain, the old shaft 
that was used for raising the rough obsidian, with relics 
of the tools and half-finished utensils. 

The inhabitants of Quito manufactured magnificent mir- 
rors from obsidian, and those of the Azores and Ascension 
islands, and Guiana, used splinters of obsidian as points for 
their lances, razors, &g. 

. Specimens of arroAvs and other articles, such as octangu- 
lar wedges, were presented a few years ago to the New 
York Lyceum of Natural History, being relics from the 
ruins of Palenque. In the collection of Columbia College 
are some razors, or sacrificial knives, the gift of the Hon. 
J. R. Poinsett. 

Obsidian occurs massive, in roundish or obtuse lumps, 
balls, and grains; has a conchoidal fracture; is semi-trans- 
parent and translucent on the edges ; it has a strong vitre- 
ous, and sometimes even metallic lustre ; its colors are 
either pure black, grayish, brownish, greenish-black, yellow, 
blue, or white, but seldom red; it sometimes displays a 
peculiar greenish-yellow shine, when it is called the irides- 



310 A POPULAR TREATISE ON GEMS. 

cent obsidian ; there is rarely more than one color in the 
same specimen with stripes and specks. Obsidian scratches 
white glass indifferently, but is scratched by topaz; its 
Btreak-powder is white ; it has a specific gra\ity of 2'34 to 
2*39. Obsidian is sometimes magnetic, so that small pieces 
show their magnetic poles. Before the blowpipe, the black 
variety is fusible with much difficulty ; and even at a white 
heat it does not melt into a solid glass; but the gray and 
bro^^n variety (marekanite) sw^ells readily into a spongy 
mass. 

Obsidian consists of silex, alumina, with a little potassa, 
soda, and oxide of iron. 

The names, Iceland agate, lava, black-glass lava, volcanic 
lava, are all synonymous, and the mineral calle'd 'bottle- 
stone, in round grains of the size of a pea, is nothing but 
a green obsidian. 

Obsidian, sometimes, forms the cement of whole moun- 
tain chains, often forms deposits in the trachyte and the 
streams at the foot of some volcano ; also, among the vol- 
canic ejections, and occurs, in loose lumps in the sand of 
rivers, and at the foot of mountains. It is found in Iceland, 
Teneriffe, the Lipari Islands, Peru, Mexico, Sicily, Hungary, 
Asiatic Russia, the Ascension Islands, and on all the vol- 
canoes of former and present times. 

In the New York Lyceum of Natural History are several 
interesting specimens, presented by Don Correa, of Ta- 
basco, from the ruins of the city of Palenque ; such as con- 
cave or triangular wedges, and other masses of obsidian, 
from various localities. 

It is employed for several useful and ornamental pur- 
poses ; such as the making of ear-rings, necklaces, brooches, 
snuff-boxes, knife handles, &c. It is particularly worn as 
mourning jewelry; it requires, however, much care in 
working, being extremely brittle. It is ground on lead 



AXINITE. 311 

wheels with emery, and polished with rotten-stone. It is 
kept in favor by the jewellers, on account of its high polish ; 
but its value is very indiiferent, excepting that of the iri- 
descent obsidian, which commands a high price, and is 
sometimes seen cut in cabochon, and set in rings. 

There is no doubt but that obsidian is of volcanic origin, 
being mostly found in the neighborhood of volcanoes, and 
that it is a glass, produced by volcanic fire, as it is a 
combination of silex and alkaline substances. The Nep- 
tunian theorists have endeavored to prove that it is occasion- 
ally found with the remains of decomposed granite, gneiss, 
and porphyry, with which it even alternates in layers. 

AXINITE. 

The name of this mineral is derived from a Greek word, 
signifying an axe, and was applied to it on account of the 
resemblance of its crystals to that implement ; it is also 
called by some English mineralogists, thumer-stone, from 
its first locality. 

Axinite occurs in a variety of crystalline forms, which 
are reducible to the rhombic, viz : an oblique rhomb, or 
four-sided prism, so compressed that the edges appear 
sharp, like the edge of an axe ; likewise, massive and in 
specks ; its fracture is uneven ; it is translucent on the 
edges, or sometimes transparent; has simple refraction 
of light ; its lustre is vitreous, also, resinous ; its colors are 
violet-blue, brown, gray, and yellow; it scratches white 
glass, but is scratched by topaz ; havS a white streak-powder ; 
its specific gravity is 3*27 ; it becomes electric by rubbing 
or heating; before the blowpipe it fuses into a grayish- 
brown glass ; acids have no efiect upon it ; it consists of 
lime, alumina, and silex, with oxide of iron and manganese. 
It occurs in gangues and layers of various formations, 



312 A POPULAR TREATISE ON GEMS. 

principally the primitive ; and is found in Daiiphine, the 
Pyrenees, Gothard, Saxony (Thiim), Norway, &c. 

This mineral takes a very high polish, particularly those 
specimens from Dauphine, but has hitherto, on account of 
its scarcity, not found much application in jewelry, but will 
hereafter be a great acquisition, as it may be used for rings, 
pins, and other small ornaments 

FELSPAR. 

The varieties of this mineral are mostly crystallized, and 
in very numerous forms ; but they are all distinguished by 
two great characters, which are, the foliated structure and 
peculiar lustre; the principal form is an obhque prism 
with unequal sides. Felsjoar scratches glass and is scratch- 
ed by rock crystal ; its streak-powder is white ; it has a 
specific gravity of 2*5 to 2*6 ; before the blowpipe it fuses 
Avith difficulty ; on charcoal it becomes vitreous and white ; 
fuses with difficulty on the edges to a translucent white 
enamel ; acids have no effect upon it ; it consists of potash, 
alumina, and silex. 

ADULARIA. 

This mineral occurs in crystals (oblique prisms and rhom- 
boidal faces), crystalline fragments, and solid masses; its 
fracture is uneven; it is translucent on the edges; has 
double refraction of light ; the lustre is vitreous and pearly, 
more especially when cut and polished ; it throws out green- 
ish and bluish-white chatoyant reflections from the interior ; 
it cleaves in two directions ; the crystals often present the 
hemitrope form, which in polished specimens becomes ob- 
vious from the different directions of the laminse; its colors 
ai*e limpid-white, greenish, grayish, and bluish, frequently 



ADTJLAEIA. 313 

with a peculiar pearly shine, and sometimes it is iridescent. 
Specific gravity, 2 '5 ; and softer than quartz. 

In commerce,* adularia goes under various names, such 
as moon-stone, sun-stone, girasol, fish-eye, and Ceylon or 
water opal. In the moon-stone the color is white, with 
small bluish or greenish shades, but the base is semi-trans- 
parent and milky; whereas the sun-stone shows a yellow 
and reddish play of col<?rs. Adularia is found in gangues 
and cavities of granite, gneiss, and limestone, and in 
pebbles from Ceylon, Greenland, Bavaria, St. Gothard, 
Tyrol, Dauphine, and in the United States, — particularly 
at Ticonderoga, near Lake Chamj)lain, New York, Mary- 
land, Pennsylvania, Connecticut, and Massachusetts. The 
adularia from St. Gothard is^ found in very large masses : I 
saw, in 1827, in the cabinet at Zurich, in Switzerland, 
groups of crystalHzed adularia, measuring two, feet in 
length and one foot in thickness, the splendor of which 
dazzled my eyes. 

Adularia, displaying a good color, and strong pearly 
reflections, is now much used in jewelry, for rings, pins, 
and other smaller ornaments. Generally specimens which 
possess these qualities are cut out of large lumps, then 
ground on a lead wheel, in cabochon form, and polished 
with rotten-stone ; they are, in general, mounted in a black 
case, whence it best shows its reflections. The moon-stone 
commands a good price ; exquisitely fine specimens, of the 
size of a bean, are worth from five to ten dollars, and some 
of them were sold at Paris, of six lines diameter, for seven 
hundred and five francs, and four lines for two hundred an^t 
three francs. 

The largest moon-stone, in a brooch, three fourths of an 
inch in length, I have seen, is in the possession of Francis 
Alger, Esq., of Boston ; and rough specimens, with most 
splendid reflections, I have admired in the collection of the 

14 



314 A POPULAR TREATISE ON GEMS. 

late Dr. M.»Gay, of the same city. Both these gentlemen 
are fortunate in possessing uniques in this country, which 
are of no ordinary scientific and commercial value. 

Among the varieties of felspar may be named ice-spar^ 
which is found in volcanic rocks, occurs crystallized in the 
Vesuvian lavas, and is of a white color. 

Murchiso7iite is a yellowish-grav variety of felspar, from 
Dawlish and Arran. 

Ledite^ or the hellefliata of the Swedes, has a peculiar 
waxy lustre and a deep flesh-red color, and is found at 
Gryphyttan, in Sweden. 

Conazeranite is a grayish-black or blackish-blue variety, 
from the steep defiles of Salleix, in the Pyrenees ; it occurs 
imbedded in limestone. 

VarioUte is a dark-green variety of felspar, containing 
lighter globular particles ; originally found in Di;ac river, 
in France, but of late also in Piedmont, Switzerland, and 
Sdotland ; in the Alps large blocks of several thousand 
pounds are found. This stone, when polished, takes a high 
gloss, equal to the most precious gems. Its name is derived 
from the peculiar spots flashing around the stone. 

The name adularia is derived from Adula, the ancient 
name of St. Gothard, where the prettiest specimens, were 
first discovered. 

A very curious variety has been found in Siberia, of a 
yellowish color, but with innumerable gold spots dis- 
seminated throughout the whole surface of the mineral ; 
these reflections of light appear to be owing to very small 
fissures or cracks, or to. a confusion of its lamellar system. 
The prettiest specimens, which are invariably cut in cabo- 
chon, look much like a reflection <^ a star, diverging from 
the centre ; they are very rare, however. This variety of 
moon-stone has often been confounded with the Oriental 
avanturine, but on examination m^y at once be detected. 



COMMON FELSPAR. 315 

The Ceylon variety ought only to be called Oriental moon- 
stone, from the peculiarity that it is more uniform, not 
striated like that from St. Gothjlrd, and having also a 
brighter lustre ; its chatoyant qualities are therefore more 
prominent. 

Sun-stone contains minute scales of mica, and reflects a 
pinchbeck-brown tint. 

COMMON FELSPAE. 

This felspar occurs in crystals, massive, and disseminated ; 
its fracture is uneven and splintery ; is translucent ; has a 
pearly and vitreous lustre ; its colors are white, gray, red, 
yellow, and green, in their various shades, sometimes with 
a variegated bluish, greenish, or reddish play of colors ; its 
texture is compact, or minutely foliated. 

The amazon-stone, or green felspar, is from Siberia ; like- 
wise splendid grass-green felspar has been found in the Uni- 
ted States, at Southbridge and Hingham, Massachusetts, and 
Cow Bay, New York ; of apple-green color, at Topsham, 
and near Baltimore, Maryland. Also, the American glassy 
or vitreous felspar, found in Delaware, which ought prop- 
erly to be quoted as a distinct species, is arranged with this 
vaiiety. » 

Felspar is widely diffused all over the globe, and wdth a 
few exceptions is more common than any other mineral; it 
forms a constituent part of most primitive rocks, such as 
gneiss, granite, &c. ; is the principal ingredient of the 
sienites, porphyry, and, in fact, with a small percentage of 
other minerals, forms whole mountain ranges and chains in 
various parts of the globe : such we see in Siberia, the north 
and west of Scotland, &c., all of which are surrounded by 
felspar. Immense beds exist in the United States : around 
Wilmington, in the State of Delaware, is an inexhaustible 
deposit of exquisite and perfectly pure felspar; and in 



316 A POPULAR TREATISE ON GEMS. 

Connecticut and on the North River we see beds of the 
foliated felspar extending for miles.* Sweden, Norway, and 
Greenland are likewise great depositories of the common 
felspar. 

The amazon-stone is used in jewelry for rings, pins, 
seals, snuff-boxes, &g. It is principally cut at Ekaterinen- 
burg, Siberia, where it is ground on a leaden wheel with 
emery, and polished with rotten-stone on a wooden wheel ; 
its form is that of cabochon, ^and sometimes that of the 
mixed pavilion-cut, when the table is to be cut pretty large, 
and arched, in order to display more distinctly its peculiar 
colors. 

Common felspar is of no great value, and only the ama- 
zon-stone is used in jewelry, which commands a good 
price. Cut specimens, suitable for ear-rings or brpoches, 
are worth from three to five dollars. 

A very fine specimen of the amazon stone, in its rough 
state, may be seen in the New York Lyceum of Natural 
History. The imperial cabinet of St. Petersburg possesses 
two vases of this stone, which are nine inches high and five 
and one half inches in diameter. Although our vitreous 
felspar has not yet been brought into use for the purposes 
of jewelry and other otnaments, yet it bids fair to con- 
tribute, at one day, much to the national wealth of this 
country, for it is the best material for porcelain, china, and 
earthen-ware. Already have many cargoes of this beautiful 
mineral been shipped to France and England (six hundred 
tons of the Connecticut, Middletown, felspar were, accord- 
ing to Professor Shephard, last year shipped to Liverpool, 
and one hundred tons to the Jersey porcelain manufactory), 
where the manufacturer appears to appreciate better the 
purity of ingredients for the purposes just mentioned. In- 
stead of receiving, as hitherto, the manufactured goods 
from abroad, made of our own raw material, it is earnestly 



LABEADOR. 317 

to be hoped that we will shortly acqun-e skill, and exert 
sufficient industry to compete with loreign manufacturers 
in the art of making porcelain, with the superior material 
which nature has so abundantly lavished on this continent. 
I possess a splendid slab of the vitreous felspar, of one 
square foot, free from any admixture, and imposing in 
appearance. 

LABEADOE. 

This mineral was heretofore considered as a variety of 
felspar; but it has latterly been separated from it, and 
ought, therefore, no more to be called labrador felspar, the 
name by which it is known in all mineralogical works. 

Labrador was first discovered by the Moravian mission- 
aries oji the island of St. Paul, on the coast of Labrador; 
and, according to others, by Bishop Launitz, in 1775, 
when it was first brought to Europe. Labrador occurs in 
crystalline masses, massive, and in boulders ; it is of an 
uneven and conchoidal fracture ; its lustre is vitreous, and 
in one direction pearly ; it is translucent ; its colors are 
gray, with its various shades, such as blackish or whitish- 
gray, with spots of an opalescent or iridescent vivid play of 
colors, consisting of blue, red, green, brown, yellow, or 
orange, according to the direction in which light is falling 
upon the specimen ; sometimes several of these colors are 
perceptible at the same instant, but more commonly they 
appear in succession as the mineral is turned towards the 
light. These colors are said to originate in fissures which 
intersect the textui-e of the mineral, as they are only per- 
ceptible from that side where they fall together with the 
foliated structure, and not like the opal, whose mass is sup- 
plied with fissures running in all directions. 

Labrador scratches white glass, is scratched by rock- 
crystal, and is somewhat less hard than felspar ; its specific 



318 A POPULAE TREATISE ON GEMS. 

gravity is 2* 71 to 2''75 ; before the blowpipe it fuses with 
difficulty, and is said to lose its play of colors ; it consists 
of silex, alumina, lime, soda, with some oxide of iron and 
water. Labrador is found as a rock and boulder, in St. 
Petersburg, Norway, Bohemia, Saxony, Sweden, St. Paul's 
Island on the coast of Labrador, and in the United States, 
in Essex county (New Jersey), at the mouth of the North 
River, and near Lake Champlain, New York, where, 
according to the description given me by Archibald Mc- 
Intyre, Esq., its splendid colors are seen on both sides of 
the water, but a few yards apart, and the effect of the rays 
of the morning sun falling upon the rock and water at the 
same time, is said to equal that of the prismatic spectrum 
thrown into a dark room. 

Labrador is used for rings, pins, buttons, snuff7boxes, 
letter-holders, cane-heads, and other ornaments, such as 
vases and larger articles ; but care has to be taken in 
grinding, that the direction where the play of colors is 
visible is kept straight, and that it is cut in cabochon. 
The price of labrador is not very high, but soon after its 
discovery, a Doctor Anderson, having described the min- 
eral as displaying all the variegated tints of color that are 
to be seen in the plumage of the peacock, pigeon, or most 
delicate humming-bird, and specimens having been carried 
to England, so great was the avidity to possess it, that 
small pieces were sold for tAventy pounds sterling. The 
present price of good specimens is from two to ten dollars; 
and a few years ago I purchased some letter-holders, which 
are beautiful specimens, for which I paid four dollars 
each. The largest specimens of labrador are in the col- 
lection of the Mineralogical Society, and in the museum of 
the Academy of Sciences at St. Petersburgh, which were 
found on the shore of the Pulkouka ; one of them weighs 
ten thousand pounds. I have in my possession a rough 



LABRADOR. 319 

specimen of the labrador of this. State, merely rubbed off 
on the surface, and its colors, I venture to say, equal, if 
they do not indeed excel, in every respect, those of the 
specimens from St. Paul?s Island ; and I anticipate the day 
when the citizens of New York will take as much pride in 
j)ossessing labrador table anfl mantel slabs, as they now do 
in employing the Italian and Irish marble for these pur- 
poses ; for the resources appear to be inexhaustible in the 
rocky county of Essex. We do not see many sj)ecimens 
brought from the coast of Labrador, and I was informed 
by Mr. Audubon, on his return from that quarter, that he 
could not find any specimens. Mr. Henderson, of Jersey 
City, who presented me the above-mentioned rough speci- 
men, had likewise splendid small polished specimens in 
breastpins, displaying all the properties in their full beauty. 
The same gentleman, who travelled last summer in com- 
pany with several scientific State geologists, mentions that 
they picked up beautiful specimens at the height of five 
thousand seven hundred feet aboVe the level of the 
sea. 

In the collection of Columbia College is a fine specimen 
of labrador, brought from Gaspe, Lower Canada, by the 
Hon. Mrs. Percival. 

In lYQO, it was announced that in Russia a labrador spar 
was discovered, where a perfect drawing .and image of 
Louis XYI. could be distinctly traced, his head surrounded 
by a colored crown of pomegranate, with a rainbow border, 
and a silvery plume of azure color ; it was what may be 
called a liisiis naturm. Count de Robassome, formerly 
in the Russian service, was the possessor of this singular 
stone, and he demanded for the same, the sum of 250,000 
francs. 

There were some magnificent specimens, tables, and 
other ornaments, in the London Exhibition. 



320 A POPULAR TREATISE ON G^MS. 

In the New York Exhibition, were likewise fine speci- 
mens exhibited from Labrador and the New York locaUty. 



HYPERSTHENE. 

This mineral was formerly annexed to hornblende, but 
has latterly been separated ; its name is derived from the 
Greek, and means of superior strength, in reference to 
the great hardness and specific gravity which it possesses. 

Hypersthene is found in crystalline masses ; it has an un- 
even fracture ; it is opaque, and its colors are dark-brown, 
red, and greenish or grayish black ; the cleavage is parallel 
to the sides, and shorter diagonals of a rhombic prism ; its 
lustre is metallic, and when viewed in one certain direction, 
copper-red, light-brown, or gold-yellow, and in others it 
has a greenish play of colors. It scratches glass, has a 
darkish-green streak-powder, and has a specific gravity of 
3*38 ; it is easily fusible before the blowpipe on charcoal 
into a grayish-dark bead ; acids have no efi*ect upon it ; it 
consists of magnesia, silex, alumina, and lime, with some 
water. . 

It is found forming a constituent of the labrador rock, 
on the coast of Labrador, Greenland, and' in the United 
States, on Brandywine creek in Pennsylvania, and in Essex 
county, New Jersey ; fine specimens- have been found in 
Hingham, Massachusetts. The French jewellers have lately 
begun to introduce this mineral for rings, pins, and other 
ornaments, on account of its high polish and beautifiil 
color. The best-colored pieces are cut out of the mass, 
and ground on a lead wheel with emery in cabochon, and 
polished with rotten-stone. Beauty of color and other 
qualifications determine the price of this stone ; at Paris a 
hypersthene, in cabochon cut, eight to ten lines long and 
six lines broad, was sold for one hundred and twenty francs. 



IDOCEASE. ^ 321 



The mineral is, however, pretty rare, and has not yet 
been fully introduced. 



IDOCEASE. 

This mineral occurs mostly crystallized, in the form of a 
four-sided j^rism, terminated by four-sided pyramids ; also, 
massive ; its cleavage is parallel to all the jolanes of the 
prism ; it is transparent and opaque ; possesses strong 
double refraction of light ; its lustre is between vitreous 
and resinous ; its cross fracture conchoidal ; the crystals 
are all striated in length; its colors are yellowish or 
brownish green, orange-yellow, sometimes blue and black. 
It scratches white glass and felspar, but is scratched by 
topaz. Its streak-powder is white, and it has a specific 
gravity of 3 '8 to 3*4. Before the blowpipe, it is fusible 
into a brownish glass. It consists of lime, alumina, silex, 
with some oxide of iron and manganese. 

Ido erase is found in different geological positions in 
primitive and volcanic rocks, in the cavities of the serpen- 
tine in the Alps, in Piedmont, Mount Somma, Vesuvius, 
Etna ; also, Norway, Sweden, Spain ; in the United States, 
at Worcester, Massachusetts ; Salisbury, Connecticut ; Cum- 
berland, Rhode Island.' 

Idocrase, of pure green and brown colors, and transpar- 
ent, is used for rings and pins, and at ISTaples and Turin, 
it is principally cut for jewelry on a leaden wheel, and is 
polished on wood with pumice-stone. The forms it receives 
are the brilliant, table, and pavilion, and if perfectly pure, 
is mounted d jour ; otherwise with a suitable foil. The 
price" of idocrase is not very high, as it is but little known 
among jewellers. 

Chrysolite and the green garnet are often substituted for 
idocrase ; but the first has a greater specific gravity and is 



322 A POPULAR TREATISE ON GEMS. 

of a more vivid color ; the latter is harder, and likewise of 
greater specific gravity. 

The Italian idocrase, which is cut at Naples, is mostly 
called the Italian chrysolite. 

HAUYNE. 

The name of this mineral was given in honor of the 
celebrated French mineralogist, the Abbe Haiiy. It occurs 
in dodecahedral crystals, with brilliant faces ; also, in grains 
and massive ; it has a conchoidal fracture ; is transparent 
and translucent ; possesses a strong vitreous lustre ; its 
structure is imperfectly foliated.- Its colors are indigo, sky, 
and smalt blue ; also, white, green, gray, and black. It 
scratches white glass and is scratched by quartz; white 
streak-powder ; specific gravity is 2'47. Before the blow- 
pipe it loses its color and fuses into a porous glass, and with 
borax into a diaphanous glass, which turns yellow on cool- 
ing; it forms a jelly wuth acids. It consists of lime, 
alumina, silex, protoxide of iron, sulphuric acid, and soda 
or potash. 

It is found in slacked basalt, and ejections of Mount Ve- 
suvius ; on Bodenmaise, on the Laach Lake, in Italy, and 
on the island of Tiree, Scotland. 

Haiiyne is not much known yet, but has lately been 
used for rings, ear-rings, brooches, &c. ; it is cut like ido- 
crase, but the price will always be high on account of its 
scarcity. 

LAPIS LAZULI. 

The name of this mineral is derived from the Persian 
language, and means blue color, or, with the Latin prefix, 
blue stone. The ancients were well acquainted with it, 
and have employed it as a substitute for other gems. The 



LAPIS LAZULI. 323 

Greeks and Romans are said to have called it by the name 
of sapphire, denominating that with specks of iron pyrites 
the sapphirus regilus ; Pliny called it the cyanus. It was 
formerly used as a strengthening medicine. 

Lapis lazuli very seldom occurs crystallized; its regu- 
lar form is th« obhque four-sided prism ; it mostly occurs 
compact, and in grains and specks, with an uneven and 
conchoidal fracture; it is translucent on the edges; its 
lustre is neai-Iy vitreous and shining; structure foHated ; its 
color is fine azure-blue, with different shades, often inter- 
spersed with spots and veins of pyrites. It scratches glass, 
but is attacked, by quartz and by the file ; its specific 
gravity is 2'3 ; before the blowpipe and on charcoal it with 
difficulty runs into a white glass, but with borax it fuses 
with effervescence into a limpid glass. It consists of Hme, 
magnesia, alumina, and silex, with soda, protoxide of iron, 
and sulphuric acid. 

It is generally called in trade, the Armenian-stone. 

It is found in gangues of the older formations, and in 
Bucharia ; it exists in granite rocks, and is disseminated 
in all veins of thin capacity ; on the Baikal Lake it is found 
in solid pieces ; also, in Siberia, Thibet, China, Chili, and 
Great Bucharia. 

Lapis lazuli is much used for jewelry, such as rings, 
pins, crosses, ear-rings, &c. The best pieces are generally 
cut out from larger lumps by means of copper saws and 
emery, then ground with emery on a lead wheel, and 
polished with rotten-stone on a tin wheel. The rocks 
which yield lapis lazuH, where it is contained in specks, 
are likewise cut for ornamental purposes, such as snuff- 
boxes, vases, candlesticks, cups, columns, cane-heads, &c. ; 
also, for architectural ornaments and stone mosaic; the 
larger specimens, having specks regularly disseminated on 
a white ground of the rock, are those selected for cutting. 



324 A POPULAK TREATISE ON GEMS. 

The most important use of this mineral is that of furnish- 
ing the celebrated and beautiful pigment called ultramarine- 
blue, used by painters in oil, and said never to fade. The 
lapis lazuli takes a very high polish, but becomes dull again 
after being used for some time. It is sometimes imitated 
by lazulite (azure-stone), or blue carbonate of copper, which, 
howeVer, is not near so hard, and effervesces on testing 
with nitric acid. Those specimens having iron pyrites 
inclosed are difficult to polish well, on account of the un- 
equal hardness of the two minerals. 

Lapis lazuli has latterly been discovered in California, 
but the color of the mineral from this IcTcality is very in- 
different, and its price is therefore much inferior to that 
from Persia. In Paris, the price is estimated at 300 francs 
per kilogramme. There are many engravings in lapis 
lazuli, such, for instance, as the Emblem of Peace — a figure 
with a torcli in one hand and a cornucopia in the other, and 
appearing to embrace military trophies, placed before her. 

The Chevalier d'Azara, Spanish minister in France, pos- 
sessed while there a very beautiful cameo of lapis lazuli, 
representing the head of Medusa, but without serpents. 
Maffei speaks of a Venus being carried by a she goat 
whipped by Love. 

The French crown-jewels contained some fine and- gigan- 
tic specimens of lapis lazuH : one in the form of a boat of 
large dimensions, valued at 200,000 francs ; a sabre-handle 
given to Lo"uis XVI., by Tippoo-Saib, valued at 6000 
francs ; a large vase, valued at 2600 fi*ancs. 

In 1855, at the Paris Exhibition, were numerous objects 
and carvings, exhibited by Rudolphi, which fairly compared 
with the antique relics of this species, both in material and 
in taste of execution. 

A marine shell carved from lapis lazuli w^as beautifully 
mounted by Morrel, and another chefd^oeuvre^ in lapis lazuli, 



LAPIS LAZULI. 325 

by Duponchel. A small round table of mosaic and lapis 
lazuli, which was a beautiful work by Jarry. 

A magnificent bagnivola of lapis lazuli, of very large size, 
and extremely pure and rich in color, was exhibited by Mr. 
Jones, in the London Exhibition, in 1851. 

Lapis lazuli has been well imitated of late, and, but for 
the touch, with much difficulty to be distinguished from 
the genuine, it is manufactured from bone-ashes and oxide 
of cobalt. 

The value of lapis lazuli, although depending upon its 
purity, intensity of color, and size, has nevertheless much 
diminished when compared with its former prices. 

The Chinese, who have for a long time employed lapis 
lazuli in their porcelain painting, call the pure and sky- 
Wue stone zuisang^ and .the dark-blue, with disseminated 
iron pyrites, the tchingtchang ^ preferring the latter to the 
former ; they work the same for many ornaments, such as 
vases, snuff-boxes, buttons, and cups. 

In the palace Avhich Catharine II. built for her favorite, 
Orlof, at St. Petersburg, there are some apartments entirely 
lined with lapis lazuli, which forms a most magnificent deco- 
ration. I have several slabs, three inches long, and of fine 
azure-blue color, in my possession. 

The produ(Sion of ultramarine has been known since 1502, 
and was already employed, under the name of azurum ul- 
trarnarinum^ by Camillus Leonarus. 

The process of preparing ultramarine was known as 
early as the fifteenth century. The color is now mostly 
prepared at Rome, in the following manner : those pieces 
which are free from pyrites specks, are first calcined and 
pulverized ; the powder is then formed into a mass with a 
resinous cement {pastello)^ and fused at a strong heat ; this 
is then worked with the hands in soft water, whereby the 
finest coloring particles are disengaged in the water. 



326 A POPULAR TREATISE ON GEMS. 

which will soon be impregnated with the blue color ; a fresh 
23ortion of water is then taken^ and the same operation is 
continued until the remains are colorless. The ultramarine, 
after a short time, settles to the bottom of the vessels, and 
is carefully separated and dried. If the lapis lazuli be of 
the best quality, the product will be from two to three per 
cent. That color which remains yet in the mass is of an 
inferior quality, and is called the ultramarine ashes ; it is 
of a paler and more reddish color. 

Good ultramarine has a silky touch, and its specific gravity 
is 2*36. It does not lose its color if exposed to heat, but is 
soon discolored by acids, and forms a jelly. In order to 
distinguish the pure ultramarine from numerous spurious 
and adulterating coloring materials, such as indigo, Prus- 
sian-blue, mineral-blue, &c., it is .only necessary to test tlje 
article in question with some acid, when after a few minutes 
the real ultramarine is discolored, yieldmg a clear solution 
and a white residuum. The real ultramarine has always 
been at a very high price, on account of the small product 
obtained from the mineral. An ounce of the purest ultra- 
marine is sold in France for two hundred to two htmdred 
and fifty francs, which is not within the reach of all painters. 

In the year 1828, the discovery was made by Professor 
Gmelin, in Tubingen, that sulphuret of soda^as the j^roper 
material for imitating this precious and valuable pigment. 
By his experiments he succeeded in preparing this substance 
from silex, alumma, soda, and sulphur, producing a color 
in every respect corresponding with the true color of the 
lapis lazuli, and bearing the same relation to acids as the 
genuine ultramarine. This, for economy, has become a 
great object to painters and color-men, since a whole pound 
of it may be purchased in France for twenty francfe. As it 
bids fair to meet with a great consumption, being even 
substituted for cobalt in bluing paper, thread, and other 



KYANITE. 327 

stuffs, several manufacturers have already been induced to 
engage largely in its preparation ; and there is now a very 
extensive establishment in full operation by M. Guimet, 
three leagues from Lyons, who likewise claims the priority 
of its discovery: the royal porcelain manufactory at Meissen, 
in Saxony, also prepares it. The process for making the 
artificial ultramarine, as it was first described by GmeHn, is 
here given, as it was published in the A7inales de Chimie. 
The whole process is divided into three parts : 

1. The pure hydrate of silica ia prepared by fusing fine 
pulverized quartz or pure sand with four times its own 
weight of salt of tartar, dissolving the fused mass in water 
and precij)itating by muriatic acid ; also the hydrate of 
alumina is prepared from alum in solution, precipitated by 
ammonia. 

2. Dissolve the silex so obtained in a hot solution of 
caustic soda, and add to seventy parts of the pure silex 
seventy-two parts of alumina; then evaporate these sub- 
stances until a moist powder remains. 

3. In a covered Hessian crucible, a mixture of dried sal 
soda, one part to two parts of sulphur, is heated gradually, 
until it is fully fused, and to the fused mass add small 
quantities of the earthy precipitate, taking care not to 
throw in fresh quantities until all the vapors have ceased ; 
after standing for an hour in the fire, remove the crucible, 
and allow it to cool. It now contains the ultramarine, 
mixed with an excess of sulphuret, which is to be removed 
by levigation ; and if the sulphuret is still in excess, it is 
to be expelled by moderate heat. Should the color not be 
uniform, levigation is the only remedy 

KYANITE, SAPPARE, DISTHENE. 

The name of this mineral is derived from the Greek, 
signifying blue, and was giv.en to it on account of its blue 



328 A POPULAR TREATISE ON GEMS. 

color. It has been known for many centuries, having been 
cut by a German lapidary, Cornellius, in the reign of James 
I., under the name of sappare, by which it is yet known 
among the French jewellers. 

It occurs in masses composed of a confused aggregation 
of crystals, and in distinct crystals of four oi* eight sided 
prisms, much compressed, with two broad shining faces. 
The crystals are generally closely aggregated, and are cross- 
ing or standing on each other in a hemitropic f(5rm, so as 
to present a singular and curious aspect. Some of the 
crystals are curved, others are corrugated or wrinkled, as 
though they had been pressed endwise, or had not room 
to stretch themselves at full length ; otliers are pressed into 
triangular shapes, &c. It has a foliated structure ; uneven 
fracture ; is transparent and translucent ; possesses simple 
refraction of light ; its lustre is vitreous and pearly ; its 
colors are azure-blue, passing into light-blue or bluish-white 
and bluish-green. It scratches white glass, and is attacked 
by topaz or a good file ; yields a white streak-j^owder ; has 
a specific gravity of 3'63 to 3*67. It becomes electric by 
rubbing, and often exhibits positive and negative electricity 
in one and the same specimen ; it is infusible before the 
blowT^ipe, but, with borax, fuses with difiiculty into a trans- 
parent limpid glass : acids have no effect upon it. 

It consists of alumina and silex, sometimes combined 
with oxide of iron and water. 

. The kyanite is found in micaceous, talcose, and argilla- 
ceous slate, at St. Gothard, in the Tyrol, and in Switzer- 
land ; in Styria, Carinthia, Bohemia, Spain, and Siberia ; 
also, in the United States, of the purest azure-blue color : 
large specimens in Litchfield, Haddam, and near New 
Haven (Connecticut) ; Chesterfield, Conway, Granville, 
Deerfield, and Plainfield (Massachusetts) ; Grafton, Nor- 
wich, and Bellows Falls (Vermont) ; Oxford (New Hamp- 



TUEQUOISE. 329 

shire) ; East Bradford, East Marlborough, and Chester 
county (Pennsylvania) ; likewise, of a delicate light-blue, 
variously shaded, in Foster (Rhode Island). 

The kyanite has not yet been received as a favorite 
among the jewellers (perhaps from not being generally 
known by them), or else it would long since have been 
cut for various ornamental purposes, more particularly in 
in this country, where the localities are so numerous and 
the color so beautiful. When well cut, it may be substi- ; 
tuted for the sapphire. I indulge the hope that some > 
jewellers or lapidaries may take a hint from this remark. 
In France and Spain, it has for some years past been used j 
for rings, brooches, and other jewelry. It is generally ' 
ground with emery on a lead wheel, and with pumice-stone 
polished on a wood plate, receiving the last polish with 
rotten-stone. The form it receives is cabochon or table 
cut. Usually, the best parts of good uniform colored speci- 
mens are picked out for cutting. 

The price of this stone depends upon the hardness, color, 
and polish : perfect specimens c(Tmmand a good price. 
Very fine cut specimens are brought from the East Indies, 
and sold in France as sapphires. 

TURQUOISE. 

The name of this mineral is probably derived from the 
country whence it was generally brought into market, 
which is Turkey. In ancient times it was used as a remedy 
for several diseases, and was also worn as an amulet against 
disasters. It occurs in reniform masses and in specks; 
has a .conchoidal fracture ; is opaque ; of a dull an^ waxy 
lustre ; its colors are blue and green, from sky-blue to 
apple-green, sometimes yellowish ; it scratches apatite, but 
not quartz nor white glass, and is easily attacked by the 



330 A POPULAR TREATISE ON GEMS. 

file ; it has a white streak-powder ; its specific gravity is 
2*86 to 3'0 ; it is infusible before the blowpipe alone, but 
loses its blue color and becomes yellowish-brown ; but it 
fuses with borax into a limpid glass. Muriatic acid has no' 
effect upon it. Consists of alumina, phosphoric acid, water, 
oxide of copper, and protoxide of iron. 

There are two kinds of turquoise used in trade, which 
differ materially in their composition, and are from differ- 
ent localities : 

1. Turquoise from the old rock, or true turquoise, which 
is generally called Oriental turquoise^ we receive from 
Persia, and is of a sky-blue and greenish color. 

2. Turquoise from the new rock, the occidental or bone 
and tooth turquoise, which is either dark-blue, light-blue, 
or bluish-green ; the surface of this mineral is sometimes 
traversed by veins which are lighter than the ground ; it is 
of organic origin, consisting, probably of colored teeth of 
antediluvian animals ; it owes its color, according to Bouil- 
lon Lagrange, to two per cent, of phosphate of iron, which 
is contained in it. " It is easily distinguished from Oriental 
turquoise by its strucfure, internally foliated and striated, 
which is an indication of a bony composition ; it does not 
take so high a polish, is discolored in distilled water, dis- 
solves in acids, and is totally destroyed by aquafortis. Its 
localities are Siberia, Languedoc in France, and other 
places. 

True or Oriental turquoise is found in small gangues of 
bog-ore and silicious schist, in boulders, &c. A mineral 
by the name of kalaite, occurring as a coating to silicious 
sinter, in Silesia and Saxony, was some years ago dis- 
covered. Turquoise is brought to market by th^ mer- 
chants of Bucharia, ready cut and polished ; and in Mos- 
cow it is wrought over, being ground on a lead wheel with 
emery, and polished with rotten-stone or pumice-stone on a 



TURQUOISE. 331 

tin wheel ; and its last and best polish is received from the 
jewellers, by rubbing with a linen rag and rouge. Since it 
is often traversed by fissures and cracks in the interior, 
it requires great caution in grinding. It is mostly cut in 
the form of cabochon ; also, as thick or table stones, and is 
used for numerous purposes in jewelry, such as rings, ear- 
rings, brooches, and also for mounting around the most 
precious gems. 

The price of turquoise has, for the last ten years, much 
decreased ; that of an Oriental is generally four times 
higher than the occidental : one the size of a pea is worth 
about five dollars ; a good turquoise, sky-blue and pval-cut, 
five lines long and four and a half -lines broad, was sold in 
France for two hundred and forty-one francs ; and a light- 
blue, greenish lustre, and oval-cut, five and a half lines long 
and five broad, was sold for five hundred francs ; whereas 
an occidental turquoise, four lines long and three and a half 
broad, brought only one hundred and twenty-one francs. 
Turquoise is very well imitated artificially (so much so as to 
render it diflScult to discover the diflference between that and 
the real), by adding to a precipitated solution of copper and 
spirits of hartshorn, finely-powdered and calcined ivory- 
black, and leaving the precipitate to itself for about a week, ' 
at a moderate heat, and afterwards carefully drying the 
same, and exposing to a gentle heat. This artificial tur- 
quoise is softer than the real, and cuts with a knife in 
shavings, whereas the genuine yields a white powder. The 
real turquoise displays in the daytime a sky-blue, and at 
night a light and greenish color; is not attacked by acids, 
and resists the fire. 

In the museum of the Imperial Academy at Moscow, is 
a turquoise more than three inches in length and one incH 
in breadth. 

A jeweller at Moscow is said to have had in his posses- 



332 A POPULAR TREATISE ON GEMS. 

sion a turquoise two inches long, in the form of a heart. 
This formerly belonged to Nadir Shah, who Avore it as an 
amulet, for which he asked five thousand rubles. 

A short time ago, I beheld, at a sale, one of the largest 
and most splendid turquoises, which was one inch in size, 
and of a blue color. 

Major McDonald's collection of turquoises, from Arabia, 
exhibited at the London Exhibition, in 1851, was very 
beautiful; it consisted of two hundred specimens, cut and 
polished. They differed very little from the Persian tur- 
quoises. He discovered several localities in the country of 
Sonalby, sixteen days' journey northeast of Suez, but all 
were within a range of forty miles, and upon a mountain 
range, at from five thousand to six thousand feet of eleva- 
tion. Some turquoises were found in situ^ but most of them 
were collected from the ravines descending, the mountain 
chain. The rock is a reddish sandstone, composed of quartz 
grainSj belonging to the paleozoic rocks. Their hardness 
is equal to that of agate. The nodules of turquoise form 
groups, almost like currant seeds, in the sandstone. There 
may be observed in this collection, veins and small concre- 
tions from one tenth to one twentieth of an inch in thick- 
ness, which cut across the bed of sandstone like small 
threads ; in color they vary from an intense blue to a bluish- 
white. 

NATROLITE. 

This mineral has been discovered of late years, and re- 
ceives its name fi-om the Latin natron^ soda, given to it on 
account of that alkali being contained in it; it occurs reni- 
form, botryoidal, and massive, such as mammillary, and in 
the alternate zones around the centre ; it has a splintery 
fracture ; is translucent on the edges ; of a pearly lustre ; 
its colors^are w^hite, yellowish-white, or reddish-brown, and 



rLUOR SPAR. 333 

they often alternate in different layers ; it scarcely scratches 
glass, but is scratched by felspar; has a white streak- 
powder; its specific gravity is 2*16; it fuses before the 
blowpipe into a colorless spongy glass*; it consists of soda, 
alumina, silex, and water, sometimes a little oxide of iron. 
Its localities are Switzerland, Bohemia, Saxony, Scotland, 
and Nova Scotia.. Natrolite, on account of its suscepti- 
bihty of a high polish, has been used for rings and other 
ornaments in jewelry' but has not yet been in much de- 
mand, and its value is also very inconsiderable. 

FLUOR SPAR. 

This mineral was well known to the ancients, but did not 
attract particular attention until the sixteenth century, 
when it was introduced as a flux. As early as 1670, the art 
of etching on glass by means of fluor spar was practised at 
Nuremberg. 

Fluor spar occurs mostly in crystals of various forms, the 
principal of which is the octahedron with its varieties, the 
cube and the rhomboidal dodecahedron ; also, massive and 
in specks ; it has an uneven or splintery fracture ; is trans- 
parent or translucent on the edges ; possesses simple refrac- 
tion of light ; a vitreous lustre ; its colors are green, yellow, 
gray, blue, and white ; also purple and red, in all their 
various shades, from the violet to the rose-red. 

It scratches lime, but not glass ; yields to the knife ; has 
a white streak-powder; its specific gravity is 3-14 to 3*17; 
it becomes electric. by rubbing; before the blowpipe it 
fuses with ebullition into an opaque globule, but with 
borax, into a transparent glass ; when pulverized and treat- 
ed with heated sulphuric acid, it emits fluoric acid gas, 
which is employed in etching on glass ; phosphoresces when 
thrown on hot iron ; it consists of fluoric acid and lime. 



334 A POPULAR TREATISE ON GEMS. 

From the variety and beauty of its colors, it is known, when 
cut, in trade, under the various names of false emerald, 
false amethyst, false ruby, and false topaz, according to the 
color it exhibits. It is mostly found .in metalliferous veins, 
and very rarely in the newer formations. Its localities are 
in Baden, Bohemia, Saxony, St. Gothard, at Derbyshire 
and Devonshire, in England, and the United States, in the 
last of which countries it occurs of most beautiful colors in 
iine crystals ; fi-om a lately-discovered locality at Russy, in 
St. Lawrence county. State of New York, I have specimens 
of crystals two feet long and five wide. It is found in Illi- 
nois, seventeen miles from Shawneetown ; Blue Ridge, 
Maryland ; Smith county, Tennessee ; at Franklin Furnace, 
and Hamburgh, New Jersey; Saratoga Springs, and at 
Alexandria, New York ; Middletown and Huntingdon, 
Connecticut ; Thetford and Southampton lead mines, Mas- 
sachusetts, and on the White Mountains, New Hampshire. 
Fluor spar is cut for ring-stones and shirt-buttons, and 
particularly in such forms as are intended to be substituted 
for other gems ; in Derbyshire there have been large mills 
for grinding, cutting, and polishing the flour spar into vases, 
cups, obelisks, plates, candlesticks, <fcc., ever since 1765, 
and there are now more manufactories, principally at 
Derby. That fluor spar which may be called the nodular 
variety, and the colors of which run in bands or zones, is 
only found in a single mine near Castleton, Derbyshire, and 
is known by the technical name of Derbyshire-spar or Blue 
John ; it is used for various ornaments, to be met with all 
over the world, in parlors or mineral collections. In order 
to heighten the various colors in the ornamental specimens, 
before they are polished, they are heated to a certain de- 
gree, when the dark spots, or tints, disappear, and the 
colored bands become more distinct, and assume a peculiar 
purple or amethystic hue. 



MALACHITE. 3^5 

Fluor spar is often intermixed with lead ore, called galena, 
which produces, when polished, a beautiful appearance. 
Ornaments of fluor spar still command a high price, which, 
however, depends a good deal on the perfect qualities of 
the various specimens, their color, size, &c. 

A translucent variety of fluor spar, called chlorophane 
(found in Cornwall, England, in Siberia, and principally in 
the United States, at New Stratford, Connecticut), is of 
beautifully variegated colors, but principally blue, violet, and 
green ; it is chiefly interesting on account of its phospho- 
rescence ; when put on hot iron in a dark room, it emits a 
most beautiful emerald-green light. One of the first locali- 
ties of chlorophane discovered in this country, was at Shee- 
konk, Massachusetts, near the summer residence of the 
Hon. Tristam Burges, about one and a half miles from 
Providence. It is massive, opaque, and of a deep purple 
color. It phosphoresces readily on being projected upon a 
moderately-heated shovel, when it loses its color and be- 
comes white. It also occurs of a crystalline structure in 
Wrentham, Massachusetts, near the Cumberland and Rhode 
Island line, in the vicinity of Diamond Hill. A beautiful 
vase of Derbyshire-spar, as also crystalline groups, may 
be seen in the collection of the New York Lyceum of 
Natural History. 

MALACHITE. 

The name of this mineral is from the Greek, alluding to 
its color ; it was well known to the ancients ; Theophras- 
tus called it the pseudo-emerald ; it was worn by many as 
an amulet. 

It occurs tuberose, globular, reniform, mammillary, and 
stalactiform ; also, in fibres ; it has an uneven, conchoidal, 
and splintery fracture ; it is opaque ; of a dull and shining 



336 A POPULAK TREATISE OX GEMS. 

lustre ; and has an emerald or verdigris green color, alter- 
nating sometimes in stripes of diiFerent shades of green. 
It scratches lime, but not glass ; its streak-powder is of 
lighter color than the mineral; its specific gravity is 3*67 ; 
before the blowpipe, it decrepitates and turns black ; with 
borax, it is reduced to a metallic grain ; it effervesces with 
nitric acid ; is dissolved, and forms a blue color with am- 
monia ; it consists of oxide of copper, carbonic acid, and 
water. 

Malachite is found in various rocks, primitive as well 
as secondary, in gangues and strata. The finest specimens 
are obtained in Siberia, Tyrol, France, Hungary, Norway, 
Sweden, England, Bohemia, and the United States, at a 
great number of localities, but either in small specimens, 
or as a coating of other copper ores, which will ever ren- 
der it useless for ornamental purposes. The principal locali- 
ties in this country are in New Jersey, Maryland, Connecti- 
cut, and at the various copper-mines ; it is also.found in the 
island of Cuba, from which place I have seen some good 
compact specimens. 

Some very fine specimens of compact malachite from 
Siberia, were presented to the New York Lyceum of 
Natural History, by Charles Cramer, Esq., of St. Peters- 
burg. I have also seen some excellent specimens of mala- 
chite in the collection of Dr. Martin Gay, at Boston ; Dr. 
Chilton, of New York, &g. 

Malachite, when cut, takes a high polish, which well 
adapts it for various ornaments, such as rings, pins, ear- 
rings, &G. Snuff-boxes, candlesticks, mosaics, &c., are like- 
wise made from it. In general, the specimens are assorted, 
and the best pieces cut on a leaden wheel with emery, and 
polished with rotten-stone on a tin plate. Very large spe- 
cimens are used for table plates and vases. 

The value of the malachite is not high, being very abun- 



MALACHITE. 337 

dant ; yet much depends upon the size of the various spe- 
cimens. At St. Petersburg, a very large slab, said to be 
in the collection formerly belonging to Dr. Guthrie, thirty- 
two inches long, seventeen inches broad,, and two inches 
thick, was valued at twenty thousand francs. Many rooms 
in several European palaces are laid out with malachite ; 
and the Mineralogical Museum, at Jena, possesses a large 
collection of malachite, which was presented, by the Grand 
Duchess of Saxe Weimar, a Russian princess. 

An apartment in the Grand Trianon, at Versailles, is 
furnished with pier and centre tables, mantel-pieces, ewers 
and basins, and enormous ornamental vases of malachite, 
the gift of the Emperor Alexander to Napoleon. 

The malachite furniture exhibited by the Russian govern- 
ment at the London Exhibition, excited so much admira- 
tion and was sold at such high prices, that the author con- 
siders himself justified in copying a part of the report by 
the jury on inlaid work in malachite : 

" Malachite is a peculiar mammillated or stalagmitic form 
of the green carbonate of copper, chiefly found in an avail- 
able state for inlaid work, in a very few localities in 
Siberia, aind lately in South Australia. It has long been 
employed in Russia in this manufacture. The mineral is 
remarkable for its fine emerald-green color (often present- 
ing several distinct shades in the same specimen), its bril- 
liant and silky lustre, and compact texture. It is softer 
than marble, very much heavier, and by no means so easily 
*Avorked, owing to its brittleness and the concentric arrange- 
ment it generally presents. It can rarely be found in 
masses weighing more than ten to twenty pounds, and 
good specimens have a very high value, as the finer kinds 
are used exclusively for decorative purposes. 

" The most important locality at present known for the 
finer kinds of Siberian malachite, is in the copper ground 

15 



338 A POPULAR TREATISE ON GEMS. 

of N'ijiig Tagilsk, in the government of Ekaterinenburg, on 
the river Tura, a tributary of the Irtish, on the Siberian side 
of the UraUan mountains, in latitude 57^° N., longitude 56° 
E. In a mine at this place, belonging to Messrs. Demidofl", 
Sir Roderick Murchison has described an immense mass of 
malachite, which at the time of his visit, a fev;^ years back, 
had been recently discovered at the depth of two hundred 
and eighty feet, strings of green copper conducting to it ; 
and these strings increasing in width and value, were found 
'to terminate in a vast irregular botryoidal mass, estimated 
to contain not less than half a million of pounds of this 
valuable mineral. The larger blocks, when exposed to the 
air, break up into smaller fragments, rarely weighing more 
than from one to four pounds. 

" It is by ilo means a modern application of this material, 
to employ it in inlaying or veneering for decorative pur- 
poses; and few palaces or large public museums in the 
principal capitals of Europe, are without specimens, mark- 
ing the progress of its manufacture from time to time, and 
generally regarded, from their great rarity, cost, and beauty, 
as worthy of being made imperial and royal presents. It 
is, however, only lately that Messrs. Demidoff, the owners 
of the mine in which the mineral occurs, have established 
in St. Petersburg a manufactory, where, after numerous 
trials and the expenditure of much capital, labor, and in- 
genuity, it has been found possible to produce such works 
as those sent to the London Exhibition, and in testimony 
of the magnitude and importance of the objects exhibited,^ 
their extraordinary beauty and richness, the excellence of 
the production, and the application of the various new 
methods of manufacture, Messrs. Demidoff have been 
awarded the highest premiums. These are chiefly seen in 
the construction of the doors, and more especially in the 
ingenious and beautiful manner in which the pattern is 



MALACHITE. 839 

ada|3ted to the material, the detaclied pieces of mineral 
being fitted to each other so as to preserve the pattern ; 
they may also be noticed in the nature of the cement, 
which being mixed with broken fragments of the malachite 
itself does not interfere w^ith the pl^n, or in any way injm-e 
the effect of the whole. 

" The working of malachite on a large scale is extremely 
tedious and laborious, and the mode of operation is too 
long to detail in this treatise. 

" The quantity of malachite obtained from the mine and 
brought into market annually is very small, and the price 
of the raw material is considerable, it ranges from twelve 
to seventeen shillings sterling per pound, according to color 
rather than veining, the darker colors being cheapest ; 
there are four shades quoted, denominated respectively, 
foncee^ ordinaire^ claire^ and pale ; but these are also sub- 
divided, the two first mto ronde and longue^ the others 
into ronde^ longue^ and tachetee. A large proportion of 
the malachite in the specimens exhibited was of very good 
color, and the average value probably exceeded fifteen 
shillings sterling per pound. 

" The objects exhibited consisted of a pair of fold- 
ing-doors, several vases, a chimney-piece, a table, a set of 
chairs, and sundry smaller articles; of these, the doors and 
vases were at once the most important and the most highly 
finished, and it is understood that the former required the 
constant labor of thirty Avorkmen employed by day and 
night during a whole year. They were most skilfully and 
and beautifully planned, and the workmanship was in all 
respects admirable." 

There are fluted Corinthian columns of malachite in 
some churches in St. Petersburg, and many other large 
ornaments of large slabs of malachite in the palace of the 
King of Prussia, at Potsdam. 



340 A POPULAR TREATISE ON GEMS. 

A large oblong table, inlaid with malachite, partly Rus- 
sian and partly Australian, was also exhibited by a manu- 
facturer of Paris, with specimens of azurite (blue carbonate 
of copper), but were all put in the shade by the Russian 
articles. 

SATIN SPAR. 

This mineral occurs stalactiform, globular, reniform, and 
massive ; it is of a fibrous texture (that is, of fine delicate 
fibres closely adhering together), a pearly lustre, and is 
translucent on the edges ; the colors are snow-white, yel- 
lowish-white, or pale-red, colored by metallic oxides. It 
scratches gypsum, but not glass; specific gravity, 2*70 ; be- 
comes electric by rubbing ; before the blowpipe is infusible, 
and changes into quicklime, but borax reduces it to a clear 
glass. It effervesces and dissolves viiih nitric acid; and 
consists of lime and carbonic acid. Satin spar is called by 
mineralogists fibrous limestone, and is found in the coal 
foriBPations, and in the cavities of several limestones. The 
finest specimens are found in Cumberland and Derbyshire, 
England ; in Hungary ; and in the United States, near 
Baltimore, in Pennsylvania, also at Westfield and Newbury- 
port, Massachusetts, where splendid specimens five inches 
long are obtained, according to Professor Hitchcock. It 
takes a fine polish, and is distinguished by its extraordinary 
fine satin lustre, and is therefore used for various articles of 
jewelry, such as ear-rings, necklaces, beads, and also for 
inlaid work ; large specimens are used for snufif-boxes. 

Satin-spar beads have been in great favor as necklaces 
and ear-rings, and were sold a few years ago in England at 
very high prices. In modern times, the satin beads or 
pearls have been imitated to a great extent in France and 
Germany, in white and deep-yellow colors : glass beads, of 
a bluish-white tinge, and hollow, are made to imitate the 



ALABASTER. 341 

reflection of the satin spar, by means of the scales of a 
small river-fish called the bleak, that are suspended in dis- 
solved isinglass, and drojDped into the bulbs, Avhich are then 
turned in all directions in order to spread the solution 
equally over their interior surface ; in this way the glass 
bulbs assume the natural color and brilliancy of satin spar ; 
they are harder, however, and it is easy to detect them on 
that account. 

Fine specimens may be seen at the New York Lyceum 
of N'atural History, also in the collection of Dr. Gay, of 
Boston. 

Satin gypsum, which bears the greatest resemblance to 
satin spar, and only differs in its chemical constituents (hav- 
ing sulphuric acid, instead of carbonic, as a component part), 
is much used for the same kind of ornamental purposes, and 
is more abundant over the world. I have seen very splen- 
did specimens at South Boston, in the beautiful collection 
of minerals belonging to Francis Alger, Esq., who brought 
them from Nova Scotia, and who (as also ^Dr. C. T. Jack- 
son) h£ls given so valuable a description of all the mineral 
treasures of that province. 

Satin gypsum is, however, much softer than satin spar, 
and is much easier scratched ; for which reason it is not 
so generally employed. 

ALABASTER. 

This mineral is a compact gypsum., and occurs massive, 
with a compact fracture ; it is translucent ; has a ghm- 
mering lustre, and its colors are white, reddish, or yel- 
lowish. 

The purest kinds of this mineral are used in Italy for 
vases, cups, candlesticks, and other ornaments. It is found 
at Castelino, in Tuscany, thirty-five miles from Leghorn, 
at two hundred feet below the surface of the earth. 



342 A POPULAK TREATISE ON GEMS. 

The yellow variety, called by the Italians, alahastro aga- 
tato^ is found at Sienna ; another variety of a bluish color, 
obtained at Guercieto, is remarkably beautiful, being 
marked with variegated shades of purple, blue, and red. 
The above alabasters are carbonates of lime. 

The principal manufactory of alabaster ornaments is at 
Valterra, thirty-six miles from Leghorn, where about five 
thousand persons live by this kind of labor. In making, 
they require great care, and must be preserved from dust, 
as the alabaster is difficult to clean. Talcum, commonly 
called French chalk, will remove dirt, but the best mode 
of restoring the color, is to bleach the alabaster on a grass- 
j)lat. Gum water is the only cement for uniting broken 
parts. 

Plaster of Paris is likewise a compact gypsum, but 
contains a small portion of carbonic acid, which makes it 
effigrvesce when treated with acids. It was formerly ex- 
ported only from Montmartre, near Paris, hence its name ; 
it is much used in ornamenting rooms in stucco, in taking 
impressions of medals, in casting statues, busts,* vases, 
time-piece stands, candelabras, obelisks, and for many other 
purposes. 

The common plaster of Paris is ground after being cal- 
cined ; and in this condition it has the property of forming 
a pliable mass with water, which soon hardens, and assumes 
the consistency of stone. 

Oriental alabaster is not a sulphate but a true carbonate 
of lime, and on account of its peculiar tint and trans- 
parency, and as it appears that it was formed similar to 
stalagmite,' it was called by the ancients, alabaster ;* the 
large vase of this Oriental alabaster , which was so justly 
and so much admired by the thousands of spectators at the 
London Exhibition, was executed by Dallamada, of Rome. 
It was really a magnificent piece of workmanship, being 



AMBER. , • 343 

from a large block and the y^^hole work of one entire piece, 
the vase, the handles, which consisted of serpents, along 
with the tazza and the extremely fine polish, displayed the 
great ingenuity of the master. 

A hollow altar of Oriental alabaster, provided with a 
lamp and intended to show the remarkable transparency 
of the material, and of excellent workmanship, along with 
a great many statues and groups of life-size figures, were 
exhibited both in the London and New York Exhibi- 
tions^ '^ 

^ AMBEK. 

This gem was known to the inhabitants of remote ages ; 
the Phoenicians sailed to the Baltic (the Glessany islands), 
for the sole purpose of obtaining ambef, which they 
wrought into chains and other ornaments, that were sold 
to the Greeks, who called the same electron. In the Trojan 
war, as Homer reports, the women wore necklaces of 
amber. Its electric properties were likewise known, for 
Thales was so much surprised at that phenomenon, that he 
attributed it to a soul in the amber ; and Pliny says that 
amber is revived by heat, the nature of electricity not 
being understood. It was also worn as an amulet, and 
used for medicine. The ancients could not agree as to its 
origin : Philemon, according to Pliny, classed it aS a fossil ; 
Tacitus, however, judging from the insects held in it, con- 
cluded it must be a vegetable juice, whence its name in 
Latin, suGcinum^ or juice. Many naturalists have, until 
lately, considered amber as a mineral; but it has been 
satifactorily proved by Schweigger and Brewster, from its 
chemical characters, and polarizing light, to be a gum-resin, 
and that it is the juice of a tree, called the amber-tree, now 
extinct. 

Amber occurs in nodules or roundish masses, from the 



344 ■ A POPULAR TREATISE ON GEMS. 

size of grains to that of a man's head ; and sometimes in 
specks ; it has a conchoidal fracture ; is transparent and 
translucent ; possesses single refraction of light ; a resin- 
ous lustre in a high degree : its colors are wine and wax 
yellow, greenish or yellowish white, or reddish-brown ; 
sometimes the colors vary in layers. It scratches gypsum, 
but is attacked by carbonate of lime ; its streak-powder is 
yellowish- white ; it has a specific gravity of 1*08 to 1*10 ; 
it becomes electric by rubbing. Before the blowpipe it 
burns'^with a yellowish and bluish green flame, emit^g at 
the same time a dense and agreeable smoke, and leaving a 
carbonaceous residuum; heated oil softens and makes it 
pliable ; it does not melt as easily as other resins, requiring 
517° Farenheit ; it yields by dry distillation an acid which 
is called succinic acid, also an essential oil, known by the 
name of oil of amber, and in the retort remains a brown 
mass, called the resin of amber, Avhich is used in the arts 
as amber varnish ; any essential oil, or spirits of turpentine 
may be used for procuring the resin ; fat oils dissolve 
amber perfectly; its elementary constituents are carbon, 
hydrogen, and oxygen, with some lime, alumina, and 
silex. 

Amber is found either thrown up by the sea, or in the 
small rivers near it ; sometimes in alluvial deposits of sand 
or gravel in the vicinity of the sea, or in bituminous forma- 
tions, such as lignite, bituminous wood, or jet, where crys- 
tallized minerals are at the same time found, such as iron 
pyrites, &c. 

Its geological distribution is in the green-sand formation, 
or, according to De la Beche, the stratified rocks, between 
the third and fourth large group. 

Amber occurs in the greatest abundance on the Prussian 
coast, in a bed of bituminous coal, where it is washed out 
or cast ashore during the autumnal storms on the coast of 



AMBER. 345 

Pomerania and Prussia proper, between Konigsberg and 
Dantzic ; it is also obtained there by sinking a shaft into 
the coal, and is mined in a systematic way. All along the 
line of the Baltic coast, at Courland, Livonia, Pomerania, . 
and in Denmark, it is picked up. On the Sicilian coast, 
near Catania, sometimes very peculiarly tinged blue, it is 
also found. In Greenland, at Hasen island, it occurs in 
brown coal. Near Paris it occurs in clay. It is also found in 
China. One of the largest specimens ever met with on the 
Baltic was found in 1811, measuring fourteen inches in 
length by nine inches in breadth, and weighing twenty-one 
pounds. 

I had in my own collection, in the year 1831, a splendid 
wax-yellow amber, from the Baltic, which measured about 
sixty cubic inches, and weighed nearly two pounds. It is 
also found on the Danish coast, and in Greenland, Sicily, 
Monrovia, Poland, France, and the West Indies. A sailor 
is said to have found a remarkable specimen, eighteen 
inches in length, in a singular manner; the discoverer acci- 
l^entally seated himself on it, when he became so attracted 
to the amber, excited by his natural heat, that it was with 
some difficulty he could detach himself from it. 

In the United States we find amber at Cape Sable, in / 
Maryland, in a bed of lignite, in masses of four and five I 
inches diameter ; also, near Trenton, and at Camden, New 
Jersey, where a transparent specimen, several inches in 
diameter, was found. According to Professor Hitchcock,! 
it is found at Martha's Vineyard, Gayhead, and at Nan- 
tucket. At the latter place, a light-colored specimen was 
found, of three or four inches diameter, which is in the 
collection of T. A. Green, Esq., of New Bedford. 

The production of amber depends upon the position of 
the respective localities ; whether it is found among sand 
and gravel, in mines called amber mines, or in the sea, on 

15- 



346 A POPULAR TREATISE ON GEMS. 

the shore, or in smaller rivers near the sea-coast ; and the 
modes of collecting are'tlu'eefold : 

1. The amber mines, which are numerous in Prussia, are 
wrought like other mines, and explored to a depth of more 
than one hundred feet. Shafts are constructed for raising 
the product from the interior of the mines ; the miners dig 
until they reach the amber vein, which is generally found 
after passing a stratum of sand and a bed of clay of twenty 
feet thickness, and another stratum of decomposing trees or 
lignite, which may be fifty feet through ; they come then to 
the pits, which the characteristic color of the soil is the best 
indication to search for. 

2. The second mode of coU-ecting amber is practised, 
generally after a storm, by the fishermen, who either wade 
into the water, provided with leather dresses, to their 
necks, or use small boats, and find at the depth of three 
fathoms the floatino- amber. 

3. It is mostly, however, collected in large quantities on 
the shore, after having been thrown up by severe storms. 

The amber fishermen are, by practice, pretty well skilled 
in finding out the spots where the largest quantities may 
be obtained. 

Amber from the mines does not essentially difier from 
that of the sea, excepting that the former is rather more 
brittle, and is often covered with an earthy crust. 

The amber is assorted before it comes into the hands of 
the lapidary or merchant, and according to size and clear- 
ness of color, it receives difi'erent technical names. Thus, 
there are — 

1. The exquisite specimens, which are perfectly pure, 
transparent, and compact, weighing from five to six ounces 
or more ; these are employed in lai'^er ornaments and spe- 
cimens of the arts, and bring the highest price. 

2. The ton stones, which weigh from a quarter of an 



AMBEK. 347 

ounce to four ounces ; the largest ot j)urest pieces of which 
are used for jewelry, and the impure for incense or med- 
icine. 

3. The nodules are still smaller. 

4. The varnish stones are still smaller than the former, 
but are very pure and hard, so as to be easily pulverized, 
and are used for varnishes, sealing-wax, &e. 

5. The sandstones are very small, opaque, and perforated 
pieces. 

6. The lumps are large but impure specimens, unfit for a 
lapidary's use ; they are sold as specimens, or employed as 
incense, or for the manufacture of succinic acid. 

7. Refuse are those pieces which fall off at the lapidary's 
bench. 

The pure amber receives from the lapidary distinct 
names, according to the shades of color it possesses, such as 
^gg^ pale, and light yellow, and so into its brownish shades. 
The assorted amber is treated according to the various 
purposes it is intended for, and receives its requisite form 
by cleaving with an appropriate instrument, by which, also, 
the external crust is removed. It is generally believed that 
the worse the crust is in appearance, the more beautiful is 
the interior of the amber. 

Amber, taking a very high polish, is employed for a 
great many purposes of jewelry, and for various ornaments, 
such as beads, necklaces, bracelets, ear-rings, buttons, rosa- 
ries, mouth-pieces for pipes, cane-heads, snuff-boxes, work- 
boxes, &c. It is generally wrought on the turner's lathe, 
by steel instruments, and is easily bored ; it is polished on 
a leaden wheel, with pumice-stone, then with linen or a hat- 
body and rotten-stone, and lastly by rubbing it with the 
hand. Common specimens are polished with a linen rag, 
chalk, and water. Beads of amber must be drilled Jjefore 
receiving the facets. In cutting and working amber, care 



348 A POPULAR TREATISE ON GEMS. 

must be taken not to overheat it by friction, as it will then 
be liable to crack. Amber has occasionally been cut into 
cameos, busts, images, &g. 

Impure amber pieces may be much imjoroved by wrap- 
ping them in paper and allowing them to digest for forty 
hours in hot ashes, in a pot filled with sand ; or by boiling 
them with gradually increased heat in linseed oil. Amber 
may also be colored red, blue, and violet, and dissolved in 
absolute alcohol ; it may be cast into different ornaments. 
Broken amber may be mended by a cement of linseed oil, 
gum mastic, and litharge ; oi- by moistening the ends of 
both, pieces with potash, warniing the same, and pressing 
the parts together. 

The price of amber was, in former times, much higher 
than at present, but size, color, and transparency always 
govern the same. A pure ^quisite specimen of one pound 
is sold for forty dollars ; but most good specimens are sent 
to Armenia, the East, and Turkey, to which places manufac- 
tured amber goods to the amount of fifty to sixty thousand 
dollars are annually exported from one manufactory at 
Stolpe, in East Prussia. 

Amber is often adulterated in various ways, and move 
especially with gum copal, which is palmed upon the igno- 
rant for amber, and which does actually resemble it in 
many respects : for both are of the same color ; both be- 
come negatively electri-c by friction ; both have nearly the 
same specific gravity; and both give a pleasant odor in 
burning ; hence when wrought as jewelry or ornaments, it 
is not easy to distinguish the one from the other. One 
mode of detection was pointed out by the Abbe Hatiy ; 
"If," says he, "a fragment of amber be attached to the 
point of a knife and inflamed, it Avill burn with some noise 
and ^ kind of ebullition, but without liquifying so as to 
flow, and if it should fall on any flat surface it rebounds a 



AMBEE. , 349 

little ; whereas copal, under similar circumstances, melts 
and falls in drops, which become flattened." My own ex- 
perience has taught me the following distinguishing charac- 
teristics : first, the electrometer, a small instrument com- 
posed of a brass needle, suspended on a pin, is the most essen- 
tial distinguishing guide, — for amber, on being rubbed, 
will excite the instrument about ten, degrees more than 
copal ; secondly, amber, on being brought before the fire, 
requires a moderately high temperature for melting it, and 
exhibits no kind of ebullition, whereas copal easily liqui- 
fies, burns with much smoke, and decrepitates more than 
amber. 

Amber is likewise adulterated by gum arable, gum thus, 
shellac, and glass pastes. The last can easily be distin- 
guished by their hardness, and the others by their solubility 
in hot water. 

Amber very frequently has inclosed within it insects, 
such as flies, beetles, &c., in a state of complete j^reserva- 
tion. Such specimens are much sought for, and command 
a very high price ; and on that account the adulterations 
are mostly practised, and in the following manner: either 
by boring a hole in the amber, introducing the beetle, 
filling it up with pulverized gum-mastic, and then let- 
ting it melt over a charcoal fire ; or by melting the amber, 
throwing in the insects, and letting it cool. The former 
adulteration may easily be detected, since the mastic will 
never be able to combine closely with the amber, and shows 
more or less cracks and fissures ; but the latter is scarcely 
to be detected, without a scientific investigation of the in- 
closed insects, which in the natural specimens do not exist 
in the present world, being called antediluvian, or extinct 
species of animals. 

The most extensive us^ of this elegant material is for the 
manufacture of the mouth-piece, an essential constituent of 



350 A POPULAR TREATISE ON GEMS. 

the genuine Meerschaum and Turkish pipe. Amber mouth- 
pieces have always been in great request in the East, where 
they command great prices ; but in the United States a fash- 
ionable taste, similar to other countries, has sprung up of 
late, which bids fair to outvie the East. • ISTo young man of 
any pretensions to smoking cigars, can do so without his 
meerschaum and amber cigar-holder. The -dearer he pays 
for this luxury, the more respected he considers himself 
There is a current belief in Turkey, that amber is incapa- 
ble of transmitting infection, and as it is a great mark of 
]X)liteness to offer the pij^e to a stranger, this supposed 
negative property of amber accounts, in some measure, for 
the estimation in which it is held. 

There is evidence of the extreme antiquity of amber in 
the fact that the Phoenicians imported it from Prussia. 
Since that period it has been obtained there uninterruptedly, 
and no diminution in the quantity annually collected has 
been perceived. If we incline to the theory that amber is 
a species of w^ax or fat, having undergone a slow process 
of putrefaction, based on the fact that chemists are able to 
convert ceraceous or fatty substances into succinic acid, by 
inducing oxidation artificially, the belief must be enter- 
tained that a new formation of amber is constantly going 
on, which theory is strengthened by the difterent appear- 
ance of the varieties of amber, which seem to exhibit the 
successive stages of its development and decay. On the 
other hand, Tacitus, in his Germania, states that it is a resin, 
exuded by certain coniferae, traces of which are frequently 
observed among the amber. Certain it is that, at one 
time, amber must have been liquid, from the simple fact 
that numerous small animals are found inclosed within it ; 
these, for the most part, are insects belonging to an extinct 
species of arachnidse. A specin5en containing the leg of 
a toad was seen among an extensive collection at the Lon- 



AMBER. 351 

don Exhibition, and it is said that in China, amber contain- 
ing insects is of frequent occurrence. From the fact that 
amber and fossil wood have been found in alluvial deposits 
of sand and clay, and associated with ocean shale and iron 
pyrites, at a depth of sixty feet, it is the author's firm be- 
lief that the marine amber is a subsequent formation to the 
terrestrial amber. That Pliny already took it for a vege- 
table production, may be inferred from his expression : 
" quod arboris succum, prisci nostri credidere." 

The different kinds of amber are distinguished by varie- 
ties of color and degrees of transparency. All shades of 
yellow, from the palest primrose to the deepest orange, or 
even brown, are its constant colors. In point of clearness, 
amber varies from vitreous transparency to perfect opacity ; 
some are nearly as white as ivory, which is, however, a rare 
occurrence. If there are two layers together, the trans- 
i:)arent and opaque varieties, it is used for cutting cameos. 
An inquiry naturally suggests itself as to which of these 
varieties of amber is the most valuable. It is self-evident 
that this must depend, as in the diamond, upon the size and 
the uniformity of the pieces. Besides, as all varieties ex- 
cepting the white, which has its special uses, are equally 
applicable for manufacturing purposes, it follows that the 
value of any particular sort must depend in a great measure 
upon its variety. The straw-yellow, slightly translucent 
variety is the most rare, and is that which the Orientals 
prefer to all others, and which they purchase- at extrava- 
gant prices. Every piece of that quality is exported to 
Turkey, in the raw or manufactured state. 

Among the exquisite specimens of amber in the London 
Crystal Palace, were four most splendid imaums, or round 
amber mouth-pieces, richly ornamented with brilliants ; the 
shortest two, which in smoking are pressed against the 
lips, were each worth three hundred pounds sterling, and 



352 A POPULAR TREATISE ON GEMS. 

were each of that peculiar color and degree of transparency 
which approaches nearest to the Turkish ideal of beauty. 
The two longer mouth-pieces were of a diiferent form, and 
although not of so good a color, nor enriched with as many 
diamonds, were still valued at two hundred pounds sterling 
each. 

A lai'ge specimen obtained from the amber pits in Pi'us- 
sia, weighing six pounds, and another marine amber and 
Avaterworn, weighing four and a half pounds, owned by Mr. 
Wolif Manheimer, of Konigsberg, Prussia, were likewise 
at the London Exhibition. 

At the Royal Museum in Berlin, is a large mass of ambei', 
weighing eighteen pounds. 

In the kingdom of Ava, a mass nearly as lai'ge as a 
child's head was found some years ago, which was inter- 
sected in various directions by veins of crystalhzed carbon- 
ate of lime. 

Amber is very fusible and liable to be broken. To join 
the broken pieces, and to unite them in such a manner as 
to look and wear as well as new, the author of this treatise 
recommends the use of soluble glass (either the silicate of 
soda, or silicate of potash), which is applied t(j the fissure 
or fractured part, after which the united parts are tied with 
with a twine and kept so for some days ; it will then remain 
firm. Thick shellac varnish is also highly recommended : 
dissolve bleached shellac in ninety-five per cent, alcohol, 
to the consistency of syrup, touch the broken parts with 
the varnish, tie them with twine, and leave the article in 
a warm place for some days before using. 

Amber powder made into a paste with thick shellac 
varnish and moulded, may easily be made into a variety of 
forms, and represent genuine amber. 

The most extraordinary collection of specimens of amber 
may be seen in the cabinet at Dantzic. A specimen of 



JET. 353 

amber of fifteen pounds weight is preserved in tlie cabinet 
at Berlin, The inhabitants of Colberg, in 15 76, presented 
to the Emperor Rudolph II. a specimen weighing eleven 
pounds. 

JET. 

This mineral occurs massive ; has a conchoidal fracture ; 
is opaque ; has a shining lustre ; and is of a jet, or pitch- 
black color. It is pretty soft, and yields to the knife; 
its hardness is 1* to 2*5; specific gravity, 1'29 to 1'35 ; 
it burns with a greenish flame, and emits a strong bitumin- 
ous smell. In trade it is also called black amber, or pitch 
coal. It is found in the brown-coal formation, the plas- 
tic clay, and the lias, with lignite and amber, in England, 
France, Silesia, Hesse, Italy, Spain, and Prussia. 

Jet bears a high polish, and is wrought into necklaces, 
ear-rings, crosses, rosaries, snufi'-boxes, buttons, bracelets, 
and particularly mourning jewelry. It is at first generally 
assorted to select the best pieces, most suitable for working ; 
such as are free from iron pyrites, lignite, and have no 
cracks or fissures. It is then turned on a lathe, and like- 
wise, on horizontal sandstone wheels, which run unequally 
on their periphery, by which the various specimens may be 
cut and polished at the same time. During the operation 
the jet must be moistened with water, else it may crack 
from being overheated. It is polished with rotten-stone or 
crocus martis and oil, on linen or buckskin ; and lastly by 
the palm of the hand. 

The manufacturing of jet ornaments was formerly a con- 
siderable branch of industry in France, where, in 1786, the 
department de I'Aube occupied twelve hundred workmen ; 
but at the present time it is not worn, and the black enamel 
is substituted for it. 

Jet is a species of bituminous coal, which has several 



354 A POPULAR TREATISE ON GEMS. 

names, such as common coal, Tblack coal, cherry coal, splint 
coal, cannel coal, jet, lignite, &g. ; more properly, how- 
ever, it is a variety of cannel coal, but it is much blacker, 
and has a more brilliant lustre. It occurs in detached 
pieces, in clay, on the coast near Whitby, in Yorkshire, 
and is the gagates of Dioscorides and Pliny, a name de- 
rived from the river Gagas, in Syria, near the mouth of 
which it was found. 

Cannel coal, which comes nearest to jet, has a dark- 
grayish, black, or brownish-black color, a large conchoidal 
fracture, and receives a good polish ; takes fire readily, and 
burns without melting, with a clear yellow flame. On this 
account it has been used as a substitute for candles, and 
hence receives its name. It is very abundant in Scotland, 
and in several parts of Ayrshire ; is wrought into inkstands, 
snuff-boxes, and other similar articles. In England the 
bituminous coal trade is a large traflic ; over one hundred 
thousand people are engaged in Newcastle, in digging. 
The principal coal mines of France are those of St. Etienne, 
Mons, Charleroi, and Liege. Germany has some coal ; but 
Belgium, Norway, Denmark, and Russia seem to be entirely 
destitute of coal beds. Some few beds are found in the 
Apennines, in Italy. In Spain, coal occurs in Andalusia, 
Aragon, Estremadura, Catalonia, Castile, and the Astu- 
rias, but not in large quantities. The only coal bed in Por- 
tugal which is worked, is situated in the province of Beira. 
Coal is also abundant in China, Japan, the* island of Mada- 
gascar, Africa, and New Holland. But nowhere are its 
deposits more extensive and numerous than in the United 
States. It occurs extensively throughout the Middle and 
Western States. The great coal formation in the United 
States is one of its principal and most striking geological 
features, and in its influence upon our industrial pursuits, 
it is unquestionably the most important of *all. The coal 



JET. 355 

measures are distributed over two principal areas, termed 
the great eastern and the great western coal fields, being 
separated from each other by a wide area of older forma- 
tions. The eastern, or Alleghany coal field, may be traced 
from near the northern limit of Pennsylvania to the south- 
west, in a line parallel with the Alleghany chain, quite to 
the central part of the State of Alabama. The antliracite 
basins, which are of comparatively small extent, lie beyond, 
or to the east of the line here traced as the limits of the 
great eastern coal field. 

From its northeasterly margin it is traced along a very 
irregular outline, as far as the Alleghany river, in "Warren 
county, Pennsylvania, and from thence it follows a direction 
nearly parallel to the shore of Lake Erie, to Portage and 
Summit counties, in the State of Ohio. From thence it 
follows a line generally parallel to its eastern margin, though 
gradually converging to its southern extremity, in Alabama. 
This coal field has a length of more than seven hundred 
and fifty miles, and an extreme breadth of on^ hundred 
and eighty miles. The superficial area has been estimated 
by Richard C. Taylor to be sixty-five thousand square 
miles; and when w^e consider the aggregate thickness of 
the difierent beds of coal over this wide extent, the ag- 
gregate amount of fossil fuel appears indeed incompre- 
hensible. 

The great western coal field, or, as it has been usually 
termed, the Illinois coal field, occupies the larger part of 
the State of Illinois, and parts of Indiana and Kentucky. 
It is separated only by a narrow belt of the lower forma- 
tions, along the Mississippi valley, from the coal fields of Iowa 
and Missouri, the extent of which has lately been shown 
to be much greater than had been supposed. Including 
the parts of this field on both sides of the Mississippi river, 
its greatest extent from southeast to northwest, or from 



356 A POPULAR TREATISE ON GEMS. 

the headwaters of Green river, in Kentucky, to its northern 
limit, on the Desmoines river, in Iowa, is more than five 
hundred miles ; while its greatest breadth across the States 
of Indiana, Illinois, and Missouri, is more than four hun- 
dred miles, and from its northern termination in Iowa to 
its present known limits, on the Osage river, at the south, 
is more than three hundred miles. This western coal field, 
therefore, including the area thus occupied on both sides of 
the Mississippi I'iver, has a much greater superficial extent 
than the eastern coal field, already described. Perhaps 
the entire area may be estimated at one and a half that of 
the Alleghany coal field, or nearly one hundred thousand 
square miles. Still farther to the south, in Arkansas, there 
is a coal field of considerable extent, which has not yet 
been fully explored ; it is probably connected with the 
Missouri field. 

There are coal fields in Michigan, Rhode Island, and 
Massachusetts, Eastern Virginia, North Carolina, near Fort 
Laramie, 'Puget's Sound, and Bellingham Bay. 

The entire area occupied by coal measures in the United 
States, east of the Rocky Mountains, is about two hundred 
thousand square miles. 

The quantity of bituminous and anthracite coal consumed 
in the United States, may be estimated at fifteen millions 
of tons annually. 

The jet of Whitby, in Scotland, forms part of a thick 
bed of lignite found there in the upper lias marls ; it difiers 
in this respect from the jet worked in France and Spain, 
which is found in irregular veins in the lower marls of the 
cretaceous series. 

Cannel coal is chiefly used in the manufacture of gas, 
but some of the harder and more compact kinds are oc- 
casionally cut into various ornamental objects, several of 
which were represented in the London Exhibition ; the most 



MEEKSCHAUM. 357 

interesting of these, as a finished work, well designed and 
well executed, was a garden seat, from the parrot coal, in 
the Fifeshire ^oal field, exhibited by His Royal Highness, 
Prince Albert ; also a model of the Durham Monument, 
and a wine-cooler, both of which were wrought from the 
N'ewcastle coal field. A set of chessmen and a snuff'-box, 
both made of cannel coal from'^China, were exhibited. In 
Roman Catholic countries, a large quantity of small orna- 
ments, such as crosses, beads, rosaries, &c., are made of jet, 
and it is generally worn for mourning decorations. 

In regard to the comparative extent of the coal fields of 
Great Britain and the United States, it may be stated that 
the former comprise five thousand four hundred square 
miles, while those of the United States contain one hundred 
and ninety-six thousand eight hundred and fifty square 
miles. The amount of workable coal in Great Britain is put 
doM^i at 190,000,000,000 tons, while that of the United 
States is set down at 4,000,000,000,000 tons, or twenty-two 
times greater in amount than the mines of Great Britain ; 
and it is well worthy the reflection of political economists, 
if we consider what has been achieved by the produce 
of the coal fields of Great Britain, what revenue must, at 
a future day, accrue to the inhabitants of the United States 
from their vast coal fields. 



MEEESCHAUM. 

This mineral is of somewhat rare occurrence. It is a 
hydrous silicate of magnesia ; has an earthy fracture, opaque, 
dull, smooth surface ; color, white, inclining to yellow, red, 
or gray; streak, shining; adheres to the tongue; has a 
hardness of 2 "5, and a specific gravity of 1*2 to 1* 6. If 
heated in a matrass, it yields water and turns black. Be- 
fore the blowpipe, it melts on the edges; with a solution of 



358 A POPULAR TREATISE ON GEMS. 

cobalt becomes red, and is decomposed by hydrochloric 
acid. 

It is fomid in nodules, at Kiltschiek, near (jonian^, in 'Ra- 
tolia, in a large fissure, six feet wide, in calcareous earth ; 
near Thebes, and in many other parts of Greece ; Yallecas, 
near Madrid, and Cavanas, near Toledo ; Pinheiro, in Por- 
tugal ; Hrubschitz and Osboweni, in Moravia, and in Swe- 
den ; but by far the largest quantity is derived from the 
peninsula of Natolia, in Asia Minor. It is called meer- 
schaum, or ecume de mer, on account of the belief of the 
workmen engaged in digging the mineral, that it grows 
again in the fissures of the rock, and that it pufifs itself up 
like froth. Good meerschaum is tolerably soft ; resists the 
pressure of the hand, but is easily indented by the finger 
nail, and especially after having been wetted ; it may be 
easily cut with a knife. 

Although the fracture is earthy, and rarely conchoi?lal, 
still the state of aggregation of pure meerschaum is very 
variable, as is proved by the marked difierence in the sjje- 
cific gravity. Some kinds sink in water, others float on 
its surface ; . and these qualities are, in the estimation of the 
pipe-maker, indicative of difi'erent values, for lie rejects 
both the very heavy and the very light, and prefers those 
of 'medium density. The light varieties are generally very 
porous, and even contain large cavities, whilst the heavier 
kinds are suspected to be an artificial product. Formerly, 
the material was roughly fashioned, on the spot, into bowls, 
which were elegantly carved in Europe. • The art was spe- 
cially cultivated at Pesth and Vienna, where it formed an 
extensive and important branch of trade. These rough 
bowls still occur in commerce ; but by far the greater part 
of the meerschaum is exported in the shape of irregular 
blocks, with obtuse angles and edges, requiring careful 
manipulation, with the aid of water, in order to remove 



MEEESCHAUM. 359 

irregularities and faulty portions. This preliminary treat- 
ment still leaves numerous blemishes. The meerschaum of 
commerce has defects of various kinds ; besides various 
minerals scattered through its mass, it contains a hard sort 
of meerschaum, which the manufacturers call chalk, and 
which is the cause of much difiiculty in the carving. Pre- 
vious to the mechanical treatment of the meerschaum for 
making the bowl, it is subjected to a certain preparation. 
It is soaked in a liquified unguent, composed of wax, oil, 
and fat; the wax and the fat which the substance absorbs, 
cause the colors which meerschaum assumes after smoking. 
Under the influence of the heat produced by the burning 
tobacco, the wax and fat pass through all the stages of a 
true process of dry distillation ; the substances thus formed 
become associated with the products of the distillation of 
the tobacco, and by their diffusion through the meerschaum, 
all those gradations of color which are so highly prized by 
the connoisseur, are produced. 

Occasionally, though rarely, the bowls are artificially 
stained, by steeping thero, before they are soaked in wax, 
in a solution of copperas, either alone or with dragon's 
blood. This process must manifestly very materially affect 
the shade of color produced in smoking. * 

The large quantity of meerschaum parings left in rough- 
ing out the bowls, would entail considerable loss, unless 
some process had been devised of rendering them available. 
A species of meerschaum bowl has long been known in 
commerce, under the name of massa bowls, which is made 
from the parings. They are triturated to a fine j)owder, 
boiled in water, and moulded into blocks, \i\\h or without 
the addition of clay. Each of these blocks suffices for one 
bowl ; but before they can be used, they must be allowed 
to dry for some time, as the j** contract considerably. These 
bowls are distinguished from real meerschaum by their' 



360 A POPULAR TREATISE ON GEMS. 

greater specific gravity ; but there is no very certain test by 
which the real meerschaum can be distinguished from the 
composition, and many suppose that all the heavier descrip- 
tions are spurious, though there is no absolute proof of 
this being the case. A negative test may, however, be 
mentioned ; the composition bowls never exhibit those little 
blemishes which result from the presence of foreign bodies 
in the natural meerschaum ; therefore, if a blemish occur 
in a meerschaum bo>vl (which is frequently the case), the 
genuineness of the bowl is rendered more probable ; but as 
these do not show until after the bowl has been used for 
some time, the test is not of much value. 

Very extensive and valuable collections of meerschaum 
pipes and mouth-pieces were exhibited in the London Crys- 
tal Palace, from Goth a, of both real and imitation meer- 
schaum bowels. From Turin, Sardinia, were elaborately- 
carved meerschaum j)ipe-bowls, the sculpturing of which 
was very exquisite. From Austria a large collection of 
massa pipe-bowls and cigar-tubes, which were manufactured 
from meerschaum dust ; the former of these articles was 
elegant, and the execution so good, that they were with 
difficulty distinguished from the real meerschaum. 

The importation of meerschaum pipes and cigar-tubes 
into the United States has of late become very extensive, 
and it was estimated at two hundred thoxisand dollars the 
last year. 

LAVA. 

This mineral is a compound of several minerals, and is a 
volcanic production. It occurs massive, with vesicular or 
porous marks ; has a splintery and conchoidal fracture ; a 
lustre dull or glistening ; is opaque, and of gray, brown, 
red, yellow, black, green, aiHi white colors, of all their 
'shades. It often contains crystals of felspar, leucite, 



JADE. 361 

hornblende, &g. In the arts, for ornamental purposes, the 
compact varieties, only, are cut and polished. In Naples, 
jewelry and ornaments in great quantities are manufactured 
and exported; such as pins, ear-rings, intaglios, snuff-boxes, 
vas€S, candelabras, &g. The different lavas are cut with 
sand and emery, and poliphed with pumice-stone. Lava is 
found in all volcanic countries, and particularly at Etna, 
Vesuvius, Ilecla, in Mexico, the Lipari Islands, &g. Lava 
is often used as the base for mosaic works. The blue lava 
of Mount Vesuvius has the appearance of artificial blue- 
enamel, and is in much demand for jewelry and ornaments. 
I have inspected fine specimens of polished slabs at the 
rooms of the Boston Society of N^atural History. 

JADE. 

This mineral is called, in mineralogical works, nephrite, 
hatchet-stone, punamu. It occurs massive ; has a splintery 
fracture ; a greasy lustre when polished ; it is translucent ; 
scratches glass, and is attacked by felspar ; it is of moun- 
tain-grass and sea-green colors ; is fusible into a greenish 
glass; it consists of silex, lime, alumina, magnesia, and iron. 
It was originally found in Cliina ; it occurs in Egypt, on 
the Amazon river, in an island in 'New Zealand, called 
Pavia Punamu, and in the United States (Smithfield, R. I., 
and Newbury, Mass,), of a sky-blue color, and a greenish 
and reddish-gray variety at Easton, Pa. 

The name nephrite is derived from vecppog^ a kidney. It 
was supposed to be a cure for diseases of the kidneys. 

It is used for snuff-boxes, cups, &c, ; and in Turkey it is 
used for handles to sabres, daggers, and hatchets. Deities 
formed of it have frequently been excavated from ancient 
ruins. . Such I saw, a few years ago, in a collection of In- 
dian curiosities brought from Mexico. 

IG 



362 A POPULAR TREATISE ON GEMS. 

• SERPENTINE. 

This mineral derives its name from its variegated color, 
which resembles the skin of a serpent. It is generally 
divided into two varieties : the common, or opaque serpen- 
tine ; and the precious, noble, or .translucent serpentine. 

Serj^entine occurs massive ; the common is occasionally 
crystallized in rhomboidal crystals, — in Norway, New Jer- 
sey, and Pennsylvania ; it has a splintery, uneven, and con- 
choidal fracture ; is unctuous to the touch ; yields to the 
knife ; its colors are green in all its shades, but also reddish 
and grayish ; hardness, 3*4 ; specific gravity, 2*5 ; is infusi- 
ble before the blowpipe, but with borax dissolves into a 
transparent glass. It does not be'long to the stratified 
rocks, but to the oj^hites of Brogniart, and is mostly asso- 
ciated with granite, gneiss ; micaceous, chlorite, argillaceous 
schists, and limestone; it therefore belongs to the primi- 
tive formation. 

Serpentine, for richness and variety of colors, exceeds all 
•other rocks; and it abounds all over the globe, in large 
consolidated masses. The finest precious serpentines come 
from Fahleen and Gulsjo, in Sweden, the Isle of Man, the 
neighborhood of Portsay, in Aberdeenshire, Corsica, Sibe- 
ria, and Saxony. Common serpentine occurs at Lizzard 
Point, in Cornwall. In the Alps we find the serpentine 
nine thousand feet high ; in France, the mountains of Li- 
mousin ; in Spain, Norway, Sweden, Scotland, the Shetland 
Isles, England, Italy, Bohemia, Saxony, Bavaria, and Swit- 
zerland ; in the United States we find it a}l along the 
Atlantic coast, where the primary rocks are found, as at 
Hoboken (New Jersey), opposite to New York city, War- 
wick (New Jersey), as far as Maryland, at Bare Hills, 
through Pennsylvania, Rhode Island, Connecticut, Massa- 
chusetts, Vermont, &g. The serpentine beds of Massachu- 



SERPENTINE, 363 

setts are inexhaustible. In Middlefield, Massachusetts, the 
bed is one quarter of a mile in breadth and six miles in 
length, which alone would- be sufficient to supply the whole 
■\A'orld with a valuable material for ornamental and archi- 
tectural purposes. There are beds at Westfield, Blanford, 
Pelham, Zoar, Windsor,* Marlborough, Cavendish, and 
other towns in Vermont. Most beautiful specimens are 
found in ISTewbury, near ISTewburyport ; and latterly a new 
locality was discovered by Dr. Jackson, in Lynnfield, 
Massachusetts. 

Serpentine incloses, chromate of iron in the Shetland 
Islands, Maryland, &g. ; and is on that account of the 
highest importance to the artist. 

It is easily wrought on lathes into various articles ; such as 
snuff-boxes, vases, inkstands, &g. ; in a small place named 
Zoblitz, in Saxony, several hundred persons are constantly 
employed in the manufacture of boxes, trinkets, and chim- 
ney-pieces. The locality at Granada, in Spain, has supplied 
many churches and palaces of Madrid with large columns, 
and other ornaments. It is really surprising that the in- 
habitants of those districts where the precious serpentine 
is found, have not yet employed it as an article of trade, as 
the quality of the American serpentine is, if not superior 
to the English and Spanish, certainly not inferior to any 
hitherto found : and I trust that the day is not far distant 
when our parlors will be embellished Avith mantel-pieces, 
tables, and mantel-ornaments, made of it. Candlesticks, 
mugs, pitchers, knife-handles, fire-iron-stands, jamb-hooks, 
and many other domestic articles, might be formed of it, 
instead of silver-plated, steel, and cast-iron ware. 

Serpentine is often associated with a number of other 
minerals : as, a, serpentine with talc ; b, serpentine with 
diallage or schiller-spar ; c, serpentine with amianthus ; d, 
serpentine with asbestos ; e, serpentine wdth garnets ; /", 



364 A POPULAR TREATISE ON GEMS. 

serpentine with actinolite, &c. That variety which contains 
amianthus in a layer, is sometimes exceedingly beautiful ; 
and when polished has the appearance of satin spar. 

MARBLB. 

This is a carbonate of hme, and a wide range of minerals 
belong to this class, containing substances which are sub- 
servient to architectural and ornamental purposes ; the 
author intends, therefore, treating this subject more exten- 
sively and giving it a wider range than other common 
minerals, and to copy from the jury report of the London 
and New York Exhibitions. 

The primary form of calcareous spar is an obtuse rhom- 
bohedron, with a great many secondary forms; has a 
hardness of 2*5 to 3*5 ; specific gravity, 2*5 to 2"7 ; it has 
a vitreous lustre, also earthy ; white or grayish-white 
streak ; color usually white, with a great variety of shades 
of gray, red, green, and yellow, also brown and black; it 
is transparent and opaque, the transparent A^arieties ex- 
hibit double refraction very distinctly ; fracture usually 
conchoidal, but obtained with difficulty, when the specimen 
is crystalline. It is composed of lime and carbonic acid, 
the colored varieties often contain in addition, small por- 
tions of iron, silica, magnesia, alumina, and bitumen, and 
acids produce a brisk effervescence ; before the blowpipe 
it is infusible, — it loses, however, its carbonic acid, gives out 
an intense light, and ultimately is reduced to pure lime, 
or quicklime. 

Calcareous spar appears under a very great variety of 
forms and aspects ; a great many species have, therefore, 
been created by mineralogists. 

Iceland spar was first aj^plied to a transparent crystal- 
lized variety from Iceland, where it was found in a cavity 



MAEBLE. 365 

ia trap, with stilbite, on the north shore of Eskifiord, on 
the east coast of Iceland ; and the property of double, re- 
fraction was first observed in this variety of carbonate of 
lime. 

Oolite consists of minute spherical particles aggregated 
by calcareous cement, so as to produce a massive structure 
and nearly earthy appearance ; it occurs in extensive beds, 
and is so dialled from its resemblance to the roe of fish, 
from woi', the Qgg. 

Pisolite^ or pea-stone, differs from oolite in the larger 
size of its particles, which are composed of concentric la- 
minae. 

Chalk is a massive opaque variety, usually white, and 
possessing a purely earthy aspect and absence of lustre, it 
is usually much softer than the other varieties of this 
species, and appears to consist in a great measure of an 
aggregation of fossils, chiefly infusorial. 

Tufa^ an alluvial deposit from calcareous springs; it 
has a very porous structure. 

Agaric mineral^ or rock milk, is a loose friable variety, 
deposited from waters containing carbonate of lime in so- 
lution, it is formed about lakes whose waters are impreg- 
nated with hme ; also in fissures in limestone, and in fime- 
stone caverns. 

Anthraconite^ or stink-stone, swine-stone, which is found 
columnar, granular, and compact, of various shades, emits 
a fetid odor when struck with the hammer. 

Stalactites are pendant masses of limestone, formed in 
limestone caverns by the percolation of waterj holding 
lime in solution, through their rocky roofs ; the evaporation 
of the water causes the deposition of the hme, and thus, in 
time, columns are often formed extending from the roof to 
the floor of a cavern ; the water which drops to the floor 
from the roof also evaporates and causes the formation of a 



366 A POPULAK TREATISE ON GEMS. 

layer of limestone over the floor ; this variety has been 
called stalaginite. 

Argentine possesses a silvery-white lustre and contains a 
little silica. 

Fontai7iebleau Ibnestone is an aggregate of secondary 
rhombohedrons, containing, mechanically mingled, large 
portions of sand ; this species in some of its forms is very 
generally diffused. 

Marble includes all the imperfectly crystalline and earthy 
varieties which admit of a high polish ; it is also called 
granular limestone, or statuary marble, which forms some- 
times entire mountains ; but more frequently occurs in beds 
in gneiss, porphyry, and mica slate. The world has been 
supplied for centuries past with statuary marble from the 
Carrara beds on the gulf of Genoa, from the islands of 
Paras, Naxos, and Tenos ; Pentillicus and Hymettus, near 
Athens, in Greece, and Schlandens, in Tyrol. 

Calcareous spar is the principal source of our polished 
marbles, the material for sculpture, quicklime, for artificial 
stone, flux for smelting ores, &c. A peculiarly fine-grained 
compact variety is employed in lithography, which is mostly 
imported from Bavaria, under the name of lithographic 
stone. 

Italy is pre-eminently the country where the manufac- 
ture of marble has been found most congenial to the 
artistic feeling of the mass of the people, and there, or in 
its vicinity, at the present day, a large part of the best 
marbles used in central Europe are obtained and worked. 
Of late years, however, France; Spain, Portugal, and j^arts 
of Germany and Belgium, have employed for their own use 
and in their own style, many useful and valuable marbles 
with which they abound, and in England manufactories 
have arisen, at first and chiefly in Derbyshire, but also in 
Devonshire and Cornwall, in which much has been done to 



MARBLE. 367 

raise the character of marble decoration, by employing the 
excellent material which abomids in those places, and by 
introducmg various useful objects of house-decoration at a 
price which, though somewhat too high for the mass of 
consumers, is far below that of foreign goods of the same 
kind in that country. Ireland, also, in which several fine 
marbles occur,, has given proof of some activity in this 
manufacture,' for which, indeed, nature has afforded many 
facilities to carry out to full advantage. 

Many marbles from Greece, Italy, and the coast of Asia 
Minor, were used by the ancients, but the quarries are now 
exhausted or concealed by rubbish. Among them may be 
mentioned the true Parian of Greek sculptors, and some 
other fine white marbles; the nero antico^ now a very rare 
black marble, considered purer and better than the known 
kinds ; the rosso antico^ a deep blood-red marble with veins 
and spots ; the verde aiitico^ a green and very beautiful 
porphyritic breccia ; the giallo antico^ not unlike the modern 
Sienna marble, of very rich yellow tint, with some others. 
Most of these are only known in sculptured specimens; but 
many, if not all the colors are closely approximated by 
recent marbles. 

The French marbles, those illustrating the Pyrenees and 
Yosges, were not less interesting. Messrs. Derville ex- 
hibited one hundred slabs of marble, each sixteen inches in 
height, comprising twenty varieties, and among them the 
marble called " girotte" (spotted with red and brown), and 
the white marble of St. Beat, all remarkable for the rarity 
of their colors and the beauty of their polish. The Campan 
marbles also possess a- peculiar geological interest in the 
number of goniatites which they inclose and which are 
often mixed confusedly with the paste; an arrangement 
which evidences the great change which these limestones 
have undergone at some period, and which proves their 



368 A POPULAR TREATISE ON GEMS. 

metamorphism, like the limestones of the State of New 
York. 

The chief marble manufacture of England is in a part of 
Derbyshire remarkable for its picturesque beauty, extend- 
ing along the valley of the Derwent and its principal 
tributary, the Wye, from below Buxton to Derby. 

The machinery for saAving and polishing was first estab- 
lished at Derbyshire at the village of Ashford, near Bake- 
well, in the year 1748, water being the motive j^ower; in 
1810, similar machinery was erected in Bakewell, and for 
many years past, also, in Derby. 

The most important marbles of Derbyshire are the black, 
the rosewood, the encrinital, the russet or bird's eye, and a 
mottled dark and light gray kind, occasionally containing 
numerous small corals. Of some of these there are several 
varieties. Others might be added to the list of those 
found" in the northern part of the county, one of which 
is a beautiful red, resembling the rosso cmtico^ but it is ob- 
tained only in small blocks or lumps. 

At Welton, in Staffordshire, near the borders of Derby- 
shire, are marbles differing much from the above, but they 
have not been brought into any considerable use, and are 
generally subject to flaws. The black inarble is of very 
fine color and texture, but large slabs free from small veins 
of calcareous spar are rare ; the best quality occurs in beds 
of from three to eight inches in thickness, some beds are 
thicker. This marble is, perhaps, superior to the similar 
kinds found in other parts of Europe and is greatly valued 
for inlaying ; it is tough and contains a good deal of carbon, 
which imparts the color. 

Black marble is extensively used for ornamental objects, 
such as vases, pedestals, chimney-pieces, &c., for which it 
is admirably adapted. 

Rosewood marble is extremely hard and of close texture ; 



MAEBLE. 369 

the beds are of considerable thickness, but the most beau- 
tiful part of the marble is only about six inches thick ; the 
name is derived from the marking of the marble beino- 
somewhat similar to that of rosewood. 

Encrinital marble is the one in most extensive use, and 
contains very numerous fossils, consisting almost exclusively 
of the broken fragments of encrinital stems, often entangled 
in coral; it -may be obtained in blocks of large superfices 
and of a thickness of two to two and a half feet. 

Russet, or bird's eye, takes its name from its color and 
appearance ; the shades varying from light-gray to brown. 
It contains numerous minute fossils, also encrinital, and is 
found in beds from six to eighteen inches in thickness. 

Dark and light mottled gray marble, called Newburgh 
marble, and the overlying bed, which is coralline, can be 
obtained from one to two feet thick. 

The "manufacture of Devonshire marble is much more 
modern, and the material is generally less manageable. 
Almost all the beautiful marbles of that county, especially 
those near Plymouth, are fossiliferous, brittle, and. very apt 
to contain veins and cracks. The marbles of Devonshire 
belong to an older geological period than those of Derby- 
shire, the latter being exclusively of the carboniferous 
limestone series, underlying the coal measures and mill- 
stone grit ; while the former are of the devonian or middle 
paleozoic epoch. 

Among the most notable marbles in the London Exhibi- 
tion, may be mentioned the following articles : 

Three chimney-pieces of Carrara marble, with many 
sculptured figures, from Milan,, in Italy; columns and 
pedestals of the madrepore marble, from a quarry in Devon- 
shire ; some pedestals of green marble, from Connemara, 
in Ireland ; a table belonging to the East India Company 
was exhibited, the top of which consists of a slice of a 

16* 



370 A POPULAR TREATISE ON GEMS. 

column from Nineveli ; several slabs of the Lumacliella 
marble, and a marble called verde di prato^ were exhibited 
fro]n Tuscany, which were extremely beautiful. A bust of 
Grattan, of Irish marble of a beautiful yellow color, at- 
tracted much attention. 

It may not be out of place to mention here the extensive 
display of marble statuary, which was also at the London 
Exhibition, — only a few will be enumerated for want of 
space : 

1. Marble statue representing Gratitude. 

2. Group representing Eve with Cain and Abel asleep in 
her arms. 

3. Marble statue of Susannah. 

4. Iconic statue in marble. 

5. Marble statue of Eve after the Fall. 

6. Marble statue representing the Greek Slave. 

7. Marble group representing Cephalus and Procris. 

8. Marble figure representing a Boy frightened by a 
Lizard. 

9. Reclining figure, in marble, representing Ishmael. 

10. Marble statue of a Boy catching a Butterfly; also, 
a marble figure representing Arethusa. 

11. Marble statue representing Giotto. 

12. Marble statue of the sculptor Flaxman, and two 
statues of the first Lord Eldon, and his brother, Lord 
Stowell. 

13. Marble group of a Girl with a Lamb, representing 
Innocence. 

14. Marble statue representing a Startled Nymph. 

15. Marble figure of a Bacchante. 

16. Marble statue of Dying Gladiator. 

17. Marble group representing an episode in the history 
• of the war between the Amazons and the Argonauts. 

18. Marble statue of Psyche. 



MARBLE. 371 

19. Marble statue representing a Girl carrying a ISTest of 
Cupids. 

20. Marble statue representing Euryclice. 

21. Marble group, — " The Orphans." 

22. A reclining marble figure of Bacchus. 

23. Model in marble of a Friar presenting the Crucifix 
to two Children. 

24. Marble bust of the poet, Yincenzo Monti. 

25. Figure in marble representing Mary Magdalen. 

26. Marble group, — Sleeping Child and Dog. 

Italian marble furnished the inaterial from which most 
of the above sculptures were wrought. 

The United States limestones, for building purposes, and 
marble for statuary, are found in great abundance, and 
many of them fairly compare with the Italian and English 
marbles. The white granular limestones are mined in many 
places ; they all belong to the newer metamorphic rocks, 
v/here they occupy a wide range, from Vermont, Massa- 
chusetts, Rhode Island, Connecticut, N^ew York, Pennsyl- 
vania, and Maryland, to Missouri ; but the best statuary 
marble has as yet only been found in the eastern part 
of Yermont: 100,000 cubic feet of good marble, suitable 
for building stone, mantel-pieces, &c., have been mined 
annually in Yermont. 

The character of the white marble varies from finely 
granular to coarsely crystalline, and from a compact, close- 
grained mass to a friable crystalline rock ; they all derive 
their existence from the metamorphism of lower silurian 
limestones. The whole range of these newer metamorphic 
rocks, from Northern Yermont as far as Maryland, yield 
abundance of the granular limestone ; along the western 
slope of the Green Mountain range, the principal localities 
are Brandon, Dorset, Pittsford, Rutland, Middlebury, 
Fairhaven, and Sudbury, in Yermont ; the principal quar- 



372 A POPULAR TEEATISE ON GEMS. 

lies in Massachusetts are at West Stockbridge, Egremont, 
Great Barrington, Lanesborough, New Ashford, Sheffield, 
and ISTew Marlborough. In 'New York, marble is quarried 
in large quantities at Hastings and Sing Sing, and Dover, 
in Dutchess county, and the range of granular limestones 
extends through Columbia, Dutchess, and Putnam coun- 
ties ; and in Connecticut the same granular limestones occur 
in abundance; also in ISTew Jersey, a few miles west of 
Philadelphia, and near Hagerstown, in Maryland. The 
marble quarries in R-hode Island, Eastern Massachusetts, 
and Maine, furnish very fine marble, belonging to the 
metamorphic limestones of a more recent date, but it is not 
as durable as those of an older age ; it is more friable, and 
has more fissures. 

Bird's-eye or encrinital marble forms an extensive bed in 
the State of N^ew York; it is a compact crinoidal lime- 
stone, containing fragments of stems and joints of crinoids 
of a bright pink, and other organic remains of a dark 
color, which, on the gray ground, give a beautiful variety. 
A similar limestone, susceptible of receiving a polish, occurs 
in the lower bed of the Niagara limestone, at Lockport and 
at Becraft's Mountain, near Hudson, where the organic 
remains are nearly similar to the first. Also the Onondaga 
limestone affords a similar marble, and taking a fine j^olish, 
Vi^ith a much greater variety of organic remains than either 
of those just described. All these limestones compose very 
thick beds, and are all suitable for ornamental purposes ; 
they are a very excellent and durable building-stone, and 
are extensively used for the massive and beautiful locks and 
piers on the Erie canal, at Lockport, and as building-stone 
in Buffalo, Lockport, and Rochester, and the city hall and 
court house in Chicago have been built from it ; they belong 
to the group of limestones called the Niagara grouj^. 

On a recent visit to Buffalo, the author's special attention 



MARBLE. 3*7 3 

was directed to the wide range of marble, beginning at 
Harlem Bridge, New York island, where the fine white 
granular marble begins ; crossing thence to Hastings, twen- 
ty miles farther up the Hudson river, of sc still finer, and 
also coarser white marble ; farther on, the Dutchess county 
white marble ; and gradually coming into the black marble 
region at Schenectady. At Little Falls, high cliffs of 
that species of limestone, with magnificent scenery, ex- 
cited his admiration on passing in 'the railroad cars. A 
short visit to the State Cabinet of Geology in Albany 
gratified him in the extreme ; and every person desirous of ^ 
being informed of the vast resources of limestone of the 
State of New York, cannot spend a more pleasant or in- 
structive day than to examine the well-arranged museum 
of the geological formation of the State of New York, and 
of the minerals of this State and neighborhood. 

A short description of this class of limestones may give 
the reader some idea of the intrinsic value of the results of 
the scientific research, accomplished through the liberally 
extended munificence of the several legislatures of the 
State, by such men as Hall, Emmons, Conrad, Mather, and 
Yannuxem. The visitor will perceive, on the entrance 
into the large hall of the Geological Cabinet, a large slab 
of the chalky limestone, with the thqusand ammonites and 
orthoceratites imbedded ; he next beholds the bird's-eye 
limestone, some specimens having also thousands of sharks' 
teeth on the surface ; he next sees the Black river and 
Trenton limestone, both rough, and also fine polished spe- 
cimens, inclosing the orthoceratite in its polished state, as 
if cut in two parts, and it makes a very beautiful appear- 
ance ; the Mohawk valley and Hudson river group, with 
ail the imbedded fossils, next attracts his attention ; the 
Utica slate and its large trilobites, from one to twelve 
inches in length, along with the Niagara limestone group. 



374 A POPULAR TREATISE ON GEMS. 

displaying likewise the gigantic trilobite family, is not less 
attractive than the enormous slab of the black limestone, 
called the corniferous limestone, with the Marcellus slirale, 
near Manlius, in Onondaga county. This slab contains 
several ammonites of one foot in length ; it is called now 
the goniatilis expansus orthoceratas marcellinius. This 
specimen must weigh at least one hundred pounds, and is 
three feet in length ; and it is certainly a very magnificent 
specimen. 

The large rhombic limestone, from St. Lawrence county, 
with the dogtooth spar, from Lockport, form interesting 
specimens in the mineralogical department of the State 
Cabinet. 

The splendid quartz crystals, from Herkimer county and 
Lake George, as also the fluor spar of Jeiferson county, and 
the beautiful green crystals of apatite, from St. Lawrence 
county, with the sulphate of strontia specimens, from the 
latter, Onondaga,, and Schoharie counties, — all claim their 
respective merits ; the labrador spar and hypersthene, from 
Essex county, the gypsum, sulphate of baryta, the beauti- 
ful rose quartz, from Fort Henry, the red sapphire crystals, 
from Orange county, and the amethysts, intermixed in 
layers with the serpentine, from Putnam county, form very 
fine ornamental mineji'als. 

Among the most interesting minerals of this State may 
be mentioned the rensselaerite, from Fort Edward ; a great 
many specimens of this interesting mineral, both rough 
and polished, may be seen in the State Cabinet. It foi-ms 
irregular masses in that limestone region, has an. unctuous 
feel of stalactite, but is of superior hardness ; resembles more 
the satin spar in its crystalline form ; it resembles pyroxene, 
but differs much from it in its hardness and specific grav- 
ity; its hardness is 3*5 to 4*, and specific gravity 2-87; its 
color is white, yellowish-white ; has uneven fracture. This 



MAEBLE. 375 

mineral was named in honor of the late patroon, Gen. 
Stephen Yan Rensselaer, of Albany. This mineral abounds 
in St. Lawrence county, and will, no doubt, at no distant 
day, be wrought into many beautiful ornaments ; the pol- 
ished specimens in the State Cabinet are very fine. 

The Potomac and breccia marble is a rock of the newer 
red sandstone series ; it forms a beautiful rock, and the col- 
umns of the hall of the House of Representatives, at Wash- 
ington, are cut from this somewhat hard material. 

The serpentine marble, or verd-antique^ occurs in nu- 
merous localities along the belt of formations which extends 
from northern Vermont, through the western part of 
Massachusetts, Connecticut, a small portion of southern 
Nev/ York, N'ew Jersey, Pennsylvania, and Maryland ; 
this formation is metamorphic of a part of the Hudson 
river group, A very beautiful verd-antique marble occurs 
at Cavendish, Lowell, and Troy, in Yermont ; in Cheshire, 
Massachusetts, and in Milford, Connecticut. There are 
two kinds of verd-antique marble — the true verd-antique, 
and the serpentine marble; the first occurs in Yermont 
and Milford, Connecticut, and the latter, called the com- 
mon, near New Haven, Connecticut. 

The white coarse-grained marble, from. Texas, Baltimore 
county, Maryland, is quarried very extensively, and used 
in Washington City for the capitol extension, treasury, and 
post-office department. 

In Missouri occur large beds of white and reddish-white 
marble, in Jefferson county and near St. Louis ; the Gene- 
vieve marble, which is an oolitic limestone, has a very 
extensive formation, and is used in St. Louis and New 
Orleans as ' building-stone ; some marble quarries are full 
of organic remains, and some are so hard and durable that 
they are used for hearths, having extraordinary power to 
resist the action of heat. 



3 76 A POPULAR TREATISE ON GEMS. 

JBreccia Marhle^ of Lancaster county^ Pennsylvania. — 
This is a recent discovery of a variegated marble, a pure 
carbonate of lime, and differs materially from other mar- 
bles of the United States and foreign countries ; and an 
independent name has been given to it by its discoverer, 
viz. : the leocacUa breccia^ which forms a solid, unstratified 
bed of compact marble. It is admirably adapted for orna- 
menting churches, banks, hotels, and otlier public buildings, 
as also for private houses for mantels, tables, wainscotmg, 
balustrades, &c. It is very easily wrought, and has, there- 
fore, the advantage of many other marbles of the United 
States. This new locality bids fair to drive the foreign and 
more costly marbles out of the market ; as for brilliancy of 
color and its variegated character, and for strength and 
durability, it has not its equal, either in the United States 
or any foreign country. It is sincerely to be hoped that 
so valuable a bed of limestone may not be left slumbering 
for another century, but that the discoverer, Mr. James W. 
Hale, may reap the benefit of its speedy development and 
general application. 

The jSTew York Exhibition of 1853 was well" supplied 
w^ith statuary from the whole world, but particularly from 
Italy. The Italian works consisted mostly of copies from 
the antique. The copy of the Flora of the Capitol; Barto- 
lini's Faith ; Harpocrates, and Cupid in a mischievous mood ; 
Canova's Hebe, and Thorwaldsen's statuary,— were all of 
great merit. Power's statues of Eve and Proserj^ine have 
been, in addition to the Greek Slave and Fisher-boy, 
already noticed among the great curiosities of the London 
Exhibition. We will enumerate the other statues in marble 
which were much admired at the New York Exhibition, 
viz. : 

1. A Bacchante, and Psyche, from the sculptor, Gait, of 
Norfolk, Va. 



MAEBLE. 377 

2. Bast of Daniel Webster ; the Husbandman's Orphan, 
a nude figure of a boy leaning on a spade ; and the Sleep- 
ing Child, — all in marble, by Pietti, New York. 

3. The Minstrel's Curse, by Miller, New York. 

4. Christ in the Sepulchre, by Creswell, Brooklyn. 

5. Bust of Dr. John Green, of South Carolina, and one 
of Charles Allen, of Massachusetts, by Kinney, of Worces- 
ter, Massachusetts. 

6. Head of a Female, by Ives, Connecticut. 

7. Bust of Daniel Webster, by King, Boston. 

8. A veiled Cupid, by Moon, New York. 

9. Head of Jupiter, and statuettes, by Ferris & Taber, 
New York. 

10. Cupid, and Charity, a female figure seated, with a,n 
infant in her "arms, life size, by Baudel, London. 

11. Busts of Daniel O'Connell and Father Mathew, from 
Hagan, Dublin. 

12. Bust of Jenny Lind, by Durham, London. 

13. Bust of Palmerston, by Sharp, London. 

14. Ruth and Naomi, by Kirk, Dublin. 

15. Bust of Louis Napoleon, emperor of France, by 
Deumier, Paris. 

16. Statue of Racine, by D'Angier, Paris. 

17. Lesbia, by L'Eveque, Paris. 

18. Damalis, by Etex, Paris. 

19. A veiled head ; a sleeping Cupid; Psyche reposing, 
and bust of Prayer, by De Bokeleer, Antwerp. 

20. Statue of Venus and Cupid, by Fraikin, Brussels. 

21. Two Children Sleeping, as a group, by Geess, Brus- 
sels. 

22. Hebe, from Canova, by Lazzerini, Rome. 

23. A Danaide, head of an Amazon, and bust of Queen 
Victoria, by Bariata, Rome. 

24. Iris, by Cartel, Florence. 



378 A POPULAR TREATISE ON GEMS. 

25. Hagar and Ishmael in the Desert, by Catelli, Flor- 
ence. 

26. Lord Palmerston, by Fabrucci, Florence. 

27. Harj^ocrates, the God of Silence, full length ; and 
Cupid in a mischievous mood, by Santarelli, Florence. 

•28. Statue of Truth, a tipsy Bacchus, and Virgin of the 
of the Eucharist, a bas-relief; by Cambi, Florence. 

29. The Betrothed, and the Son of William Tell, by 
Romanelli, Florence. 

30. The Genius of Sacred Music, and Laura, by Consani, 
Florence. 

31. The Sleep of Innocence, by Dupri, Florence. 

32. John the Baptist sleeping, by Magi, Florence. 

33. Death of Ferruccio, by Giampaoli, Lucca. 

34. Rebecca, Faithful Love, the Child's First Grief, bust 
of Cleopatra, and bust of Heloise, by Yaspi, Florence. 

35. The Mendicant, by Strazza, Rome. 

36. Shepherdess and Bird, the Guardian Angel, and 
Psyche sorrowing, by Bimaimi, Rome. 

37. Cupid leaning on a wine-skin, by Strechi, Rome. 

38. Cupid wdth the arms of Mars, the Sacrifice of a God, 
and three Female Dancers, by Jerichau, Rome. 

39. Columbus, Staffetti, Carrara. 

. 40. A Bacchante, a nymph wreathing herself with flow- 
ers, the Genius of Summer, the Genius of Spring, Herminia 
writing the name of Tancred, and Poetry, by Pelliccia, 
Carrara. 

41. Cupid, Psyche, and Venus of the Louvre, by Fabri- 
cotti, Carrara. 

42. The Flora of the Capitol, Bartolini's Faith, the 
Dying Gladiator, bust of the Saviour, St. John the Baptist, 
bust of Rousseau, by Baratta, Carrara. 

' • 43. Pope Pius IX., by Tenerasie, Carrara. 
44. Bust of Washington, by Bagazzi, Carrara. 



MARBLE. 379 

45. Copy of the Warwick Yase, Flora of the Capitol, the 
Pet Bird, Apollo Belvidere, Copernicus, Diana of the 
Louvre, Dante, Jupiter, Shakspeare, Madonna, and Faith, 
by Marchetti, Carrara. 

46. Marcus TuUius Cicero, and Paris, by Fontana, Car- 
rara. 

47. The Shepherdess and Lamb; a Struggle for the 
Heart, by Orlandi, Carrara. 

48. Ceres, Yenus, Child with a Bird, Psyche, Poetry, 
and Yincenzo Gioberti, by Bruneri, Turin. 

49. The Yii-gin mourning over the dead body of Christ, 
by Angero, Turin. 

50. The Yirgin and Angel of Annunciation, by Galeazzi, 
Turin. 

51. Hebe offering ISTectar to the Eagle, by Kachszman, 
Milan. 

52. Boy riding on a Craw^fish, a Tortoise, Leda with the 
Swan, Innocence, and veiled head, by Croff, Milan. 

53. Atala and Chactas, colossal bust of the Redeemer, 
by Fraccardi, Milan. 

54. Infant Saviour, Child on the Waves, by Galei, Milan. 

55. The Deserted, veiled head, Cupid forcing the Roses, 
nest of Cupids, cage of Cupids, and basket of Cupids, by 
Motelh, Milan. 

56. Sleeping Yenus, by Rados, Milan. 

57. Resignation, by Tandardini, Milan. 

58. The Fisher-boy, by Cacchi, Milan. 

59. The Soldier's Son, by Jorini, Milan. 

60. Head of the Saviour, and colossal bust of Yincenzo 
Monti, by Langiorgio, Milan. 

61. Yirgin grieving, by ISTezeo, Milan. 

62. Eve after the Fall, by Ragani, Milan. 

And many more, less notable. All of these sculptures 
were in Italian marble. 



380 A POPULAR TREATISE ON GEMS. 

Stalactite and Stalagmite. 

It occurs in large tuberous, undulated masses, botryoidal, 
manimillary, or concretional, either in icicles or circVes ; 
has a fibrous fracture ; is translucent ; of a pearly lustre ; 
color generally yellowish-white and white ; its composition 
is calcareous spar ; it originates in caverns, through which 
water, holding this in solution, filters, and on its ultimate 
evaporation leaves the carbonate of lime in various forms, 
which sometimes resemble altars, pillars, animals, &c. 

Those pillars or icicles which are pendant from the roof, 
and those rising from the base, are sometimes divided into 
stalactite for the former, stalagmite for the latter. But the 
cause of their existence is the same, and there ought not 
to be any distinction in their name. 

Ornaments of stalactite in the shape of vases, &c., are 
often seen in fancy stores. The greatest localities of this 
mineral are, the Grotto of Antiparos, and Bauman's Cave, 
in the Hartz, which I visited in 1827, and which displays 
gigantic stalactites; also in Derbyshire. In the United 
States, are very celebrated caves which yield this article. 

These have been described by my friend, Charles Cra- 
mer, Esq., late Russian Vice .Consul at New York, now 
of the Isle of Wight, an . enthusiastic minei'alogist, of St. 
Petersburg, in a pamphlet published by the Imperial 
Mineralogical Society of St. Petersburg, in the German 
lano:ua2:e: and as this interestino^ little work is not accessi- 
ble to all, I will here translate the list of all the caves enu- 
merated by him as North American. We would observe 
that these are not all situated in limestone regions, neither 
do they all furnish stalactites. 

Canada. — Grotto in the Niagara ; a cave in Lanark, 
Upper Canada ; a smaller cave at the same place. 

N'ew Hampshire. — The Devil's cave. * 



MARBLE. 381 

Vermont. — Caves in BeDnington ; caves in Dorset. 

Massachusetts. — IsTatural bridge and cave at ISTahant ; 
natural bridge over the Hudson brook ; cave near Sunder- 
land ; cave in Berkshire ; two caves near ISTew Marlbo- 
rough ; cave near West Stockbridge ; cave in Lanesboro ; 
cave in Adams ; Purgatory, near Sutton. 

Connecticut. — West Rock cave, New Haven. 

Rhode Island. — Purgatory, near Newport ; Spouting 
cave, near Newport. 

New York. — Cave near Watertown ; cave at Niagara ; 
Ball's cave ; Knox's cave ; Monito, at Wigwam, or Devil's 
Abode ; Esopus cave. 

Pennsylvania. — Devil's Hole, in Bucks county ; cave on 
the Swatera river. 

Maryland. — Hughes' cave ; cave at Harwell. 

Virgmia. — Weber's cave ; Wreast's cave ; Madison's 
cave; Zane's cave; Blowing cave, near Panther Dale; 
Greenbriar's cave ; cave on the Kanhawa river ; Chaj^in's 
cave ; Johnson's cave ; Allen's cave ; Ruffner's cave ; Roger's 
cave; Reid's cave ; Natural Tium el in Scott county; Natu- 
ral Bridge in Rockbridge connty. 

Ohio. — Mason's cave ; Nature's Building, or Cave in the 
Rock. 

Indiana. — Epsom Salt cave ; cave near Corydon. 

Kentuchy. — Boone's cave ; Russell's cave ; White cave; 
Mammoth cave ; cave on Crooked creek. 

Tennessee. — Big-bone cave ; Arched cave. 

South Carolina. — Great Flat Rock cave ; Lover's Leap. 

Georgia. — Nicojack cave. 

Missouri. — Ashley's cave. 

Mississippi. — Abode of the Great Spirit on the North 
Weat Coast ; cave on Copper river. 

Mexico. — Dantoe cave ; Chamacasapa cave ; San Felipe 
cave. 



382 A POPULAR TREATISE ON GEMS. 

Cuba. — Cave 'near Matanzas. 

Hayti. — Cave near St. Domingo. 

Peru. — Cave in the Andes. 

New Andalusia. — Canipe cave. 

Mr. Cramer mentions the size of .the stalagmites in the 
antechamber of Weyer's cave, as being twelve feet high ; 
those in Solomon's Temple, of the same, twenty-five feet 
high, which are nearly transparent ; and its Hermit's Chan- 
delier, four feet high, and twelve feet in circumference ; the 
colossal stalagmite in Washington Hall, which is said to 
represent the Father of his Country wrapped in his cloak ; 
Pompey's column, thirty feet high ; also Babylon's Tower, 
thirty feet in circumference. 

Egyptian Marhle. 

This is generally milk-white, or grayish-white and bluish, 
and also black and red, which is called the rosso antico; it 
is of a close granular structure, and was a great favorite 
with the ancient architects. 



Italian Marbles. 

' With these may be counted the Parian marble ; the Pen- 
telian marble ; the Venetian or Lombardy marble, which 
is quite translucent ; the Luni and Carrara marble ; and the 
Laconian marble, or verd-antique. They have all yielded 
materials for the most ancient Greek and Italian sculptors. 
The Venus de Medici, the Diana Hunting, and Venus leav- 
ing the Bath, are of Parian marble ; a Bacchus in repose, a 
Jason, a Paris, and many Grecian monuments, are from 
Pentelian marble, which comes from the vicinity of 
Athens. 



MAEBLE. 383 

American Marhle. 

{Additional from tlie former edition of this treatise.) 

The varieties of marble, which substance is inexhaustible 
in the United States, .are very numerous ; and I am proud 
to assert, that for architectural and ornamental purposes, 
they will successfully compete with those of any foreign 
country. The colors are various, from the snow-white to 
the black with gold and grass-green veins. A small dis- 
trict in New England, of about fifty miles in extent, con- 
centrates, I may say, the marbles which may be collected 
in Europe through a space of two thousand square miles ; 
for w^e find in the county of Berkshire, and that of New 
Haven, the representatives of marbles from Italy and Ire- 
land ; and the discoveries which are constantly being made 
of additional marble localities are a source of great satis- 
faction. Thirty years ago, the City Hall, of New York 
city, was built of marble from West Stockbridge, Massa- 
chusetts, which was transported at great expense, a dis- 
tance of over four hundred miles ; whereas, afterwards, the 
same quality of marble was discovered on New York island, 
but a few miles distant. According to Professor Dewey, 
the county of Berkshire alone turned out forty thousand 
dollars' worth of marble several years ago. I will here 
enumerate a few of the most interesting marbles : 

a. The Philadelphia marble, which is snow or grayish 
white, and sometimes variegated with blue veins, which 
takes a very high polish. 

h. The Potomac marble, which is properly called a 
breccia, being composed of rounded and angular frag- 
ments from the size of a pea to that of an ostrich's egg. 
Its colors are red, white, gray, and blackish-brown, inter- 
mixed ; it takes a very fine polish, and forms a most beau- 
tiful ornamental stone. It comes from the banks of the 



384 A POPULAR TREATISE ON GEMS. 

Potomac, in Maryland. As specimens of this, we would 
refer to the columns in the House of Representatives at 
Washington, which are twenty feet high, and two feet in 
diameter. 

c. The Yerd- Antique, of Kew Haven, Connecticut. This 
marble is intermixed with serpentine veins, and makes a 
most beautiful appearance. There are inexhaustible quar- 
ries of it at New Haven and Milford ; it bids fair to rival 
every other ornamental stone in the world. Four chimney- 
pieces of this mineral wei'e purchased for the Capitol at 
Washington ; and I lately examined a splendid centre 
table, wholly cut from this marble, that was exhibited at 
the tenth annual fair of the American Institute. It is to 
be hoped that some company may undertake to introduce 
this marble more extensively into notice, for it does not.yet 
appear to be sufficiently known among our wealthy citi- 
zens: the enterprise would be well rewarded. Large slabs 
may be seen at the New York Lyceum of Natural History, 
and in the cabinet of Yale College, New Haven. I possess a 
very fine, large slab, polished. Portsmouth, Vermont, like- 
w^ise furnishes splendid verd-antique, specimens of which 
may be seen at the American Institute, in New York. 

d. Berkshire county, in Massachusetts, may justly be 
called the marble pillar of the United States ; and, as Pro- 
fessor Hitchcock remarks, the inhabitants of that county 
cannot but regard their inexliaustible deposits of marble 
as a rich treasure to themselves, and an invaluable legacy 
to their posterity. The towns. West Stockbridge, Lanes- 
borough, New Ashford, Sheffield, New Marlborough, and 
Adams, in that county, keep thousands of hands constantly 
working in their quarries. In 1827, two thousand seven 
hundred tons of marble were exported from that town ; and 
in 1828, a block of from fifty to sixty feet square, and eight 
thick, v/as raised by one charge of gunpowder. 



MAEBLE. 385 

e. White, fine, granular marble, bearing the closest re- 
semblance to the celebrated Carrara marble, is obtained 
from Smithfield, Rhode Island ; Stoneham, Massachusetts, 
and near Hastings, on the Hudson river. 

SMI Marble. 

This mineral is a secondary marble, and is called also 
conchitic marble, on account of its containing petrified 
shells, which, when polished, communicate to their matrix, 
the marble, a most beautifully variegated appearance. 

a. The Lumachella marble is a kind which is very scarce; 
it has a gray or brown ground, interspersed with shells of 
a circular form and golden color, and when held towards 
the reflection of light, displays red, blue, and green tints, 
like those of the precious opal or iridescent labrador. 

It is sometimes seen in the form of pins and other jewelry, 
but stands, on account of its scarcity, very high in price ; 
the only locality is in Carinthia ; one formerly in Devon- 
shire, England, being exhausted. Some splendid specimens 
from Carinthia, are in the collection of Baron de Lederer, 
Austrian consul for this city ; and a very fine specimen of 
the lumachella, at the Boston Society of ISTatural History, 
was marked with the locality of Neufchatel. 
• b. Pdnno di niorto^ or funeral pall, is a deep black 
marble, with white shells, like snails ; it is only seen at 
Rome, and is very scarce. 

c. Bristol marble, from England, is a black marble, inter- 
spersed with white shells. , 

d. Italian shell marbles from Florence, Lucca, and Pisa, 
are red, containing white shells (ammonites). 

e. French shell marbles are very numerous ; tliose from 
Narbonne are black with white belemnites ; that from 
Caen is a brown marble with madreporites ; and those from 

17 



386 A POPULAR TREATISE ON GEMS. 

Languedoc are of a fiery red color, mixed with white and 
gray univalve shells ; of this Napoleon's eight columns for 
his triumphal arch in the Carousel, at Paris, were cut. 

f. The United States have a great many shell-marble 
quarries ; but they are all black and gray. Those of Tren- 
ton Falls, Little Falls ; near Seneca lake ; Northumber- 
land county, Pennsylvania; Bernardston, Massachusetts, 
and Hudson, New York, contain either trilobites or encri- 
nites ; some take a very fine polish. 

PISOLITE AND OOLITE. 

These minerals are likewise composed of carbonate of 
lime; they occur massive, and in distinct concretional 
layers, either in the form of peas or other round grains or 
pebbles, and are of white, yellowish-white, brownish, or 
reddish color ; when cut and polished, they make a fine 
ornamental stone, and present a very effective appearance. 
The former is found in alluvial deposits of the hot water 
mineral springs of Carlsbad, in Bohemia, and the baths of 
St. Philip, in Tuscany ; the latter forms large beds in Eng- 
land and France. The city of Bath, in England, is mostly 
built of this limestone. 

ROCK OF GIBRALTAR. 

This is likewise a carbonate of lime ; occurs massive, 
mostly striped ; is yellowish-white, yellow, and brownish ; 
is only found in that rock from whence it takes its name, 
and has been heretofore a great favorite for jewelry and 
other ornaments. At this day we see in shops and private 
houses, pins, brooches, ear-rings, seals, cane-heads, snuff- 
boxes, letter-holders, vases, urns, candelabras, obelisks, &c.j 
formed of it. It takes a high polish. 



APATITE. 38'; 



APATITE. 



This mineral was namfed by Werner, on account of its 
color being so deceptive {anaraw, to deceive), as it resembles 
the color of some other precious stones; it occurs in six- 
sided prisms, massive and globular ; has a conchoidal frac- 
ture ; a vitreous lustre ; color usually sea-green, bluish-green, 
or violet-blue, sometimes white, occasionally yellow, gray, 
•and red ; is transparent and opaque ; it resembles the beryl 
and emerald, but is distinguishable by color and hardness ; 
hardness, 4"5 to 5 ; specific gravity, 3 to 3'235. A bluish 
opalescence is observed in the direction of the vertical axis, 
in some specimens, especially in the white variety; fracture 
conchoidal and uneven ; brittle. Some varieties are phos- 
phorescent when heated, others become electric by friction. 
It is infusible alone before the blowpipe, except at the 
edges ; dissolves slowly in nitric acid, and without effer- 
vescence. 

Apatite usually occurs in primitive rocks ; is often found 
in veins of primitive limestone traversing granite, — it also 
occurs in serpentine and in ancient volcanic rocks. 

It contains about ninety per cent, subsesquiphosphate of 
lime, and the rest is chloride and fluoride of calcium. On 
account of its phosphoric acid, the compact varieties of 
apatite have become an important article of trade for agri- 
cultural purposes. 

The principal localities are in Saxony, at Ehrenfriders- 
dorff, in the .Hartz mountains, where the author collected, 
in his youthful years, some magnificent crystals ; also in 
Bohemia, at Schlackenwald ; in Cumberland and Devon- 
shire, England ; at St. Gothard, in Switzerland ; and a 
greenish-blue variety, called moroxite, is found in Norway, 
at Arendal. 

Asparagus stone, which is of a yellow color and trans- 



388 A POPULAR TREATISE ON GEMS. 

lucent, is found at Estremadura, in Spain, of whi-ch many 
fine specimens may be seen at the Academy of Natural 
Sciences of Philadelphia, — in Maclure's collection ; also in 
Zillerthal, Tyrol, where it is imbedded in talc. The phos- 
phorite, or massive varieties, from Spain and Boheinia, has 
been found in large beds. In the United States it occurs 
in a vein of limestone intersecting the granite at Gouver- 
neur, St, Lawrence county, New York, and crystals of 
ten to twelve inches long and one and a half to two inches, 
in diameter, of fine sea-green color, were formerly found 
in abundance. 

Yale College has some fine specimens of this crystallized 
variety, from Baron Lederer's cabinet. Professor Shep- 
herd, Mr. Francis Algar, and Dr. Charles T. Jackson, in 
Boston, possess many fine and large crystals. Mr. Kranz, 
in Bonn,' was fortunate to procure, through his collector, 
some gigantic crystals of this beautiful mineral. There are 
some other localities of the crystallized variety in the 
United States, such as Amity, New York, where it occurs 
of a green color in white limestone, presenting the primary 
form, and accompanied with pyroxene and scapolite. Crys- 
tallized and massive specimens of a bluish-green color 
occur at Boston, Massachusetts, associated with sphene and 
petalite. Reddish-bro^\Ti crystals, of one inch in length, 
have been obtained from a granite vein in Greenfield, New 
York. The massive variety of phosphate of lime from 
Crown Point, New York, has furnished several thousand 
tons for export to England as a fertilizing agent, and the 
concretion al variety of phosphate of lime from Dover and 
Franklin, in New Jersey, has likewise yielded considerable 
quantities for a manure. These two latter varieties have 
been treated with sulphuric acid* (oil of vitriol), in order to 
obtain a superphosphate of Jime, which is now considered 
the most useful vehicle to enrich the soil, and to produce 



MICA. 389 

the most prolific crops. Liebig and Johnstone, the two 
great agricultural chemists, have demonstrated beyond any 
controversy that the resuscitation of worn-out soils depends 
materially upon the addition of phosphate of lime ; and 
hence the application of bone-dust, which is a phosphate of 
lime, and guano, which contains the latter ingredient with 
the amm-oniacal salts in combination, of which at the 
present day 100,000 tons are annually consumed by the 
farmer, along with the artificially prepared superphosphate 
of lime, are well known, but do not belong here. 

LEPIDOLITE. 

This mineral derives its name from the Greek language, 
from its scaly structure ; it occurs massive, j)resenting an 
aggregate of minute, shining, flexible scales or hexagonal 
plates ; 'it has a splintery fracture • a glistening and pearly 
lustre ; is translucent on the edges ; its colors are lilac, 
rose-red, pearl-gray, greenish-yellow, and blue ; it is 
scratched by glass, and yields to the knife ; has a specific 
gravity of 2 "81 ; is fusible with ease into a transparent 
globule. It is found in granite and primitive lime, in 
Monrovia, France, island of Elba, Corsica, Sweden, and in 
the United States, in Maine, New Hampshire, Vermont, 
and Massachusetts. It is cut m Europe for various orna- 
ments, such as plates, vases, snuff-boxes, &c., and will, I 
trust, at some future day, be more extensively used in 
jewelry ; for there are some variegated specimens of a 
peach-blossom color, and very fine granular structure, 
which are extremely beautiful. 

. MICA. 

This mineral occurs crystallized, in six-sided tables and 
oblique rhombic prisms, and massive ; also, disseminated ; 



390 A POPULAR TREATISE ON GEMS. 

it has a perfectly foliated structure ; a glittering and 
metallic lustre ; is transparent and translucent ; very fusi- 
ble and elastic ; its colors are white, green, black, brown, 
peach-red, yellowish, and bluish ; it has a specific gravity 
of 2*7. It is found in primitive rocks, and forms an ingre- 
dient in granite, gneiss, mica slate, and other rocks, where 
it more or less predominates ; its localities are, therefore, 
universal, but in Siberia it forms large beds, and is quarried 
for special i:)urposes, such as a substitute for glass windows ; 
and although the United States afford ample localities of 
it, yet a few years ago quantities w^ere imported here for 
the doors of Nott's stoves. 

The lolumose mica is a beautiful variety, and derives its 
name from its resemblance to a quill or plume, the lamellar 
or fine delicate crystals diverging in such a manner as to 
present this appearance. It is of a pearl-gray color. It is 
found in the United States, at Williamsbury, Mass., Hart- 
ford, Conn., and many other places. The gre^rkmica is of 
a beautiful grass-green color, and is found in Brunswick, 
Maine. The rose-red mica is a very beautiful mineral, and 
is found in numerous places, in this country ; principally at 
Goshen, Chesterfield, Mass. ; Acworth, IST. H. ; Bellows 
•Falls, Yt., &c. Mica may, when Of good colors, be used 
for jewelry and other ornamentg, as well as the lepidolite. 



PYRITES. 

This mineral is called sulphuret of iron, iron pyrites, and 
markasite. It occurs crystallized in many forms ; such as 
the cube, octahedron, and dodecahedron ; also massive, 
disseminated, capillary, and cellular; it has a conchoidal 
fracture ; a brilliant metallic lustre ; its colors are bronze, 
yellow, brass-yellow, and steel-gray. This mineral ta^^es a 
very high polish, and from its fine lustre looks extremely 



POEPHYRY. , 391 

well when cut in the form of a brilliant or rose. It was 
formerly much used in jewelry for ear-rings, rings, pins, 
and necklaces. It was, in former times, considered a great 
preservative of health. It is now but seldom seen, except 
in mineralogical cabinets. 

ROSE MANGANESE. 

This mineral is called in mineralogical works the silicious 

oxide of manganese, and also the carbonate of manganese. 

*It occurs massive ; has a foliated structure ; a conchoidal 

fracture ; a shining lustre ; it scratches glass ; its colors are 

rose-red, reddish, and yellowish. 

It is found in Siberia, Sweden, Hungary, England ; and 
in the United States, at Middlebury, Yt., and at Cumming- 
ton and Plainfield, Mass., where, according to Professor 
Hitchcock, the silicious oxide, or according to Dr. Thomp- 
son, the bisilicate of manganese is found in great abundance. 
Since it takes a very high polish, and is much wrought at 
Ekaterinenburg, in Siberia, into many ornaments, it is con- 
fidently to be hoped that it may also find its amateurs in 
this country, as it is very easy to cut and polish, and the 
material is so plenty. 

PORPHYRY. 

This mineral forms rocks in a geological sense, but is 
properly a compact felspar. It has various colors and 
shades, and contains imbedded crystals of felspar and 
quartz. The name porphyry signifies purple, from Trop(f)vpa, 
such having been the usual color of the ancient porphyries ; 
the same rock exhibits, however, almost every variety of 
color ; it is the hardest of all rocks, and when polished, is 
probably the most enduring. It is much used in Europe 
for ornamental and architectural purposes ; also for slabs, 
mortars, and other articles. 



392 A POPULAE TREATISE ON GEMS. 

In the United States, porphyry has never been used for 
any purpose; but Professor Hitchcock remarks, in his 
Geological Report of the State of Massachusetts, that it 
would be strange if an increase of wealth and refinement 
should not create some demand for so elegant and enduring 
a rock as porphyry. In the same excellent work the author 
divides porphyry into four varieties, as occurring in Massa- 
chusetts, in tlie neighborhood of Boston : 

1st. Compact felspar, with several predominating colors; 
the one with yellow, resembling the Turkey stone; one^ 
with red, from brownish to blood-red, closely resembling 
jasper ; one with a rose-red color, resembling the rose petro- 
silex of Europe. 

2d. Antique porphyry; closely resembling that European 
porphyry which was employed by the ancients in monu- 
ments and ornamental furniture and forms, and is, Avhen 
polished, a beautiful ornament. It presents numerous vari- 
eties and shades of color : one of the most elegant is the 
light-green ; then a deep-green ; red of various shades ; 
reddish-brown ; black, or nearly so ; gray, and purple ; and 
the imbedded crystals are usually of a light color, some- 
times white, brown, and greenish. 

3d. Porphyry with two or more minerals imbedded, and 
having a base of common felspar. This mineral is between 
sienite and porphyry, resembling the trachytic porphyry, 
and is generally unfit for ornamental purposes ; the quartz 
which it contains is hyaline and smoky. 

4th. The brecciated porphyry, which is composed of an- 
gular fragments of porphyry and compact felspar, reunited 
by a paste of the same material ; the fragments are also of 
various colors, usually, however, gray and red ; the rock is 
very hard, and when polished, furnishes specimens of great 
delicacy for ornamental purposes. 

Porphyry is much used in*England for paving stones, in 



SIENITE. 393 

the entrance halls of large public buildings or private 
mansions, and the Cornwall porphyry is particularly cele- 
brated for its various tints of colors. The author distinctly 
recollects four slabs : one was a black slab ; another, red ; 
a third, green; and a fourth, a large slab, containing 
twenty-four specimens of various variegated rocks of por- 
phyry. Also, the elvan-stone, from the quarries of New 
Quay, in Cornwall, which is a beautiful porphyry. The 
large slab, weighing about eight hundred pounds, was of 
very fine red color ; it 'was without flaw or defect. 
, In Prussia porphyry is abundant, and there were some 
fine specimens in the London Exhibition, such as a table, a 
small column and tazza ; the latter was a round slab of red 
color and fine texture, and the tazza vase and pedestal were 
of the same material. 

From Sweden and Norway a sienitic porphyry, of gray- 
ish-red color, was also in the London Exhibition. 

The porphyry vase in the Berlin Museum, which, accord- 
ing to the author's recollection, is about eight feet high 
and six feet in diameter, is well deserving a place in this 
treatise, as it is unique of its kind in the world. • 

SIENITE. 

This rock is composed essentially of felspar and horn- 
blende, and sometimes contains quartz or mica, or both. 
When polished, it forms the most splendid ornamental 
stone of all rocks ; it is very hard ; and its color and the 
mode of distribution of the various ingredients, make it 
very agreeable to the eye. It much resembles granite, and 
is often almost identical with it ; but by close inspection it 
may be distinguished from the want or addition of the 
component ingredients. 

Professor Hitchcock describes six varieties of sienite: 

17* 



394 A POPULAR TREATISE ON GEMS. 

1st. That sienite which is composed of felspar and horn- 
blende, when the first is white, greenish, and yellowish, and 
the latter invariably black. 

2d. Felspar, quartz, and hornblende ; the first is foliated, 
and commonly, of grayish, bluish, or yellowish color ; the 
second from quite light to dark color and hyaline ; and the 
latter is black. Under this variety the quarries at Quincy 
and Cape Ann have been arranged by the author (which 
are generally called granite), on account of the absence of 
mica. The Quincy granite, or rather sienite, is that cele- 
brated architectural material used in the cities of Boston 
and New York, for those huge and magnificent edifices, 
public as well as private, erected within the last six years ; 
"knd it may be supposed that five thousand buildings in the 
city of New York have been constructed with this splendid 
article. 

3d. Felspar, hornblende, quartz, and mica. This rook, 
likewise, has a beautiful appearance, but is, as yet, less 
wrought than the other varieties. The felspar and horn- 
blende are predominant. The quartz is in small grains, and 
the mica is black. 

4th. Porphyritic sienite ; its base is quartz and felspar, 
and the hornblende is almost entirely absent ; it has a 
porphyritic aspect ; the felspar predominates. It is the 
most ornamental stone when jDolished. 

5th. Conglomerated sienite; it is a quarternary com- 
pound of felspar, hornblende, quartz, and mica, but all in 
rounded or conglomerated masses, having the aspect of a 
pudding-stone; the nodules are from half an inch to six 
inches in size, and may be easily broken out of the mass, 
and the hornblende predominates mostly in them. It is 
unfit for architectural purposes. 

6th. Augite sienite ; in this rock tjie hornblende is 
present and mica absent. It is composed of black horn- 



SIENITE. ' 395 

blende, greenish augite, and yellowish felspar ; all, except 
the felspar, presenting a crystalline structure ; it is also 
composed only of augite and felspar. 

The name of the rock sienite was originally derived from. 
Syerie, in Upper Egypt, from whence the first specimen 
was procured ; it was examined and identified hj Werner ; 
many of the Egyptian monuments, such as Cleopatra's 
Needle, and Pompey's Pillar, were obtained from there. 

There are valuable quarries of sienite in abundance in 
the State of New Ygrk. It is a durable and beautiful 
stone, and may be quarried in large blocks, but on account 
of its great hardness requires much labor to dress it. 

Along the North River there are many localities : An- 
thony's Nose, or Anthony s Face, which is a mountain in 
the northwest corner of Putnam county, opposite Fort 
Montgomery. It is called so in consequence of the profile 
bearing a rude resemblance to the human face, that may 
be seen in one position, when passing it ; but on account of 
its steepness, being five hundred feet in height, it is more 
generally called Breakneck Mountain. Here is the granitic 
sienite. It is composed of a darkish-gray colored felspar, 
with a little black hornblende. 

In Peekskill bay, on the Hudson river, and the adjoining 
hills for five miles in length, very valuable quarries of this 
fine rock may be quarried. 

The sienite rock of the Highlands is very extensive ; 
such as the Target rock on Constitution Island, opposite 
West Point, and all along the slopes of the mountains in 
the Highlands, there are boulders and blocks of this valu- 
able and useful rock. 

Fort Putnam, near West Point, and the base of Butter 
Hill, four miles north of West Point, are composed of sienite. 

When it was ascertained that the famous rock from 
Syene, in Upper Egypt (so much employed in ancient 



396 A POPULAR TBEATISE ON GEMS. 

monuments), and from which the name of sienite was de- 
rived, was nothing but granite with black mica, and also, 
that Mount Sinai, in Arabia, was composed of genuine 
sienite, a French geologist proposed to substitute sinaite 
for sienite, but the name, although a good one, has never 
been adopted. 

The Quincy and Cape Ann sienite, which is sent from 
Massachusetts to all parts of the United States, and forms 
such a beautiful architectural material, is composed of 
felspar, quartz, and hornblende. 

GRANITE. 

This rock is composed of quartz, felspar, and mica, and 
forms the crust of our globe. It occurs over the whole 
earth, and the eastern part of the United States is abund- 
antly furnished with this valuable mineral. As a building 
material it has been most extensively used for the last ten 
years ; but the great fire in New York, which, in Decem- 
ber, 1835, consumed seven hundred buildings, among 
which about two hundred Avere of granite, has given a 
Rufiicient proof that granite is, in this changeable climate, 
unfit for a building material, but that it may be usefully 
employed for ornamental and architectural purposes, where 
it is not constantly exposed to the atmosphere and weather, 
which make it so liable to decomposition. 

Nevertheless, granite continues to be generally employed 
in the erection of public buildings, warehouses, bridges, 
&c., and begins to form an important pecuniary object to 
the merchant and .mechanic ; and on this account I cannot 
forbear to treat more fully on its general characters, and I 
must confess that the rich granite treasures of Connecticut, 
Rhode Island, and Massachusetts, which I had occasion to 
examine a short time since, on a journey into those regions, 



GEANITE. 397 

deserve fully all the encomiums bestowed upon them in 
Hitchcock's Report on the Geology of Massachusetts, and 
in Shepherd's Report on the Geological Survey of Connec- 
ticut. So abundant and large are the granite rocks in the 
eastern part of the United States,* that some single locali- 
ties are sufficient to supply many countries with this lucra- 
tive article. 

Professor Hitchcock divides the granite of Massachusetts 
into four varieties, viz : 

1. Common granite, which, according to him, embraces 
nine tenths of the granite in Massachusetts : the ingre- 
dients are a distinct crystalline structure, of mixed and dis- 
criminating colors. 

2. Pseudomorphous granite is that variety in which the 
mica separates distinctly the other ingredients, which are 
closely mixed. 

3. Porphyritic granite : it contains, besides the usual 
composition of quartz, felspar, and mica, distinct imbedded 
crystals of felspar. 

4. Graphic granite : this variety consists of quartz and 
felspar only ; the cross-fracture presents the appearance of 
written characters. 

Professor Shepherd divides the ornamental granite of the 
State of Connecticut into eight difterent types, viz. : 

1. Gray granite. 

2. White granite. This variety I have examined myself 
in Plymouth, Connecticut, and so beautiful was its color 
and close granular texture, that I took it at a distance for 
a sandstone, or white marble. 

3. Flesh-colored granite. 

4. Red granite. 

* Professor Hitchcock remarks that there is not a town in Massachusetts 
in •which more or less granite does not occur, either as situ or as boulders. 



398 A POPULAR TREATISE ON GEMS. 

6. Epidotic granite. 

6. Porphyritic granite. 

7. Chloritic granite. 

8. Sienitic granite. 

In Rhode Island a fine white granite has, according to 
Dr. Webb, of Providence, been employed for the erection 
of the arcade of that city, from a quarry in Johnstone, five 
miles from Providence. 

The manner in which granite is usually split out at the 
quarries, is this : a number of holes, of a quadrangular 
form, a little more than an inch wide and two or three 
inches deep, are drilled into the rock at intervals of a few 
inches, in the direction in which it is wished to separate 
the mass. Iron wedges, having cases of sheet iron, are 
then driven, at the same time and with equal force, into 
these cavities ; and so prodigious is the power thus exerted, 
that masses of ten, twenty, thirty, and even fifty and sixty 
feet long, and sometimes half as many wide, are separated. 
These may be subdivided in any direction desired ; and it 
is common to see masses thus split till their sides are less 
than a foot wide, and their length from tefn to twenty feet. 

The price of the granite from these quarries, according 
to Professor Hitchcock, is from forty to forty-five cents per 
superficial foot, and for hammering and fine dressing it, 
about thirty cents the superficial foot, such as in the style 
of the Tremont House in Boston ; common work from 
twenty to thirty-five cents ; posts for stone fronts cost 
thirty-four cents per foot. The enterprising citizens of the 
city of New York have erected gigantic monuments of 
granite, for future generations to admire. 

New York abounds in granite, both east and west of the 
Hudson river, Staten Island, Westchester and Putnam 
counties. In the city of New York, a large bed of fine 
granite extends from Thirty-first street on the west side, 



GEANITE. 399 

and from Twenty-fourth street in the middle, to Sixtieth 
street on the north. The Croton Aqueduct is mostly 
built of granite quarried in Tenth avenue near Forty-eighth 
street. 

Granite abounds in Rockland and Orange counties ; it 
occurs in beds, veins, and irregular masses, forming hills, 
and often the tops of mountains. 

The fine-grained varieties of granite are best for eco- 
nomical uses. When granite contains distinct crystals of 
felspar, it is called porphyritic ; wh^n the ingredients are 
blended into a finely granular mass, with imbedded crys- 
tals of quartz and mica, it is called by French writers, 
eurlte. A granular mixture of quartz and felspar is called 
I^egmatite, 

In England, Cornwall is particularly celebrated for its 
granite ; the obelisk from the Lamorran quarries, twenty- 
two feet high, which was ex'hibited at the London Exhi- 
bition, was twenty-one tons in weight, and of a coarse 
grain, and another, from Cornseco granite, weighing thirty- 
one tons, and eighteen feet high, were beautiful specimens 
of this useful rock. They were each wrought from a single 
block of granite, and were remarkable for extreme fineness 
and closeness of grain, and the delicacy of finish which was 
thereby obtained. 

The granite column of Cheesewing granite, the property 
of the Prince of Wales, near Liskeard, in Cornwall, was 
likewise a magnificent piece. It was thirty feet high. 

The bust and pedestal of blue Peterhead granite was 
also an interesting specimen of its kind. 

Swedish granite has been known for many centuries ; it 
is obtained from extensive quarries on the island of Ma- 
leuva, on the west coast of Sweden. It bears a high polish. 



400 A POPULAR TREATISE ON GEMS. 



PEARLS. 

Pearls are concretions, consisting of carbonate of lime, 
having a roundish, tubercular, or angular form ; a .white, 
gray, blue, or green color ; a shining lustre, and the hard- 
ness of lime; specific gravity, 2*68. They are found in 
several bivalve shells — the meleagrina margaritifera, haliotis 
gigas, and haliotis iris, and a large species of tuiHDO, which 
shells are known in commerce as flat shells, ear shells, green 
snail shells, buffalo shells, and Bombay shells ; many unios, 
alamadontas, &c. Mother of pearl is the internal or nacre- 
ous layer of such shells. These precious substances are the 
result of an excretion in superimposed concentric laminae of 
a peculiarly fine and dense nacreous substance, which con- 
sists of membrane and carbonate of lime. The finest qual- 
ity is produced by the bivalve of the Indian seas, called par 
excellence the pearl oyster {rrieleagrina margaritifera). In 
the United States the alasmadonta arcuata, corresponding 
wdth the mytilus margaritiferus of Barnes, the unio ochra- 
ceus, unio complanatus, and many other species, contain 
the pearls, and according to the nacre of the shells the 
color of the pearl is corresponding. 

The origin of pearls is by some considered to be unfructi- 
fied eggs ; by others, a morbid concretion or calculus, 
produced by the endeavor of the animal in the shell to fill 
up holes therein ; by others again, as mere concretions of 
the juice of which the shell has been formed, and with 
which the animal annually augments it. It is very plausi- 
ble, however, that the animal of the shell is attacked often 
by enemies, such as the boring shells (turritella), &c. ; that 
grains of sand, or any other pointed substance, which, on 
such occasions, come within the shell, stick fast and aug- 
ment with the growth of the shell ; it is also known that 
pearls may be produced artificially, by pressing a sharp 



PEAELS. 401 

body on, or by boring a hole in, the shell. The Chinese 
are in the habit of laying a string with five or six small 

' pearls separated by knots, inside of the shells, when the fish 
are exposing themselves to the sun, and taking them out 
after some years, whereby they obtain very fine and large 
pearls, and but a little open on the side where they were 
adherent to the shell. The pearl fishers say that when the 
shell is smooth and perfect, they never expect to find any 
pearls, but always do so when it has begun to be deformed 
and distorted. It w^as therefore concluded, that as the fish 
grew old, the vessels containing the juice for forming the 
shell and keeping it in vigor, became weak and ruptured, 
and from this juice accumulating in the fish, the pearl was 
formed, and the shell brought to decay, as supposed by M. 
Reaumur. , It would be, according to this idea, a sure 
guide to know from the form of the shell, whether the 
pearl is large or small ; and thus by the smaller ones being 
thrown back into the sea, a constant crop of large pearls 
might be obtained. The mother-of-pearl fish is found in 
the East and West Indies, and other seas in warm latitudes, 
and in the rivers of north and middle Europe. In some 
parts of the globe, they are found in clusters, containing a 
great number; the places where found are called pearl- 
banks. The most famous are near the coast of Ceylon, 
that of Japan, and in -the Persian Gulf, near the island of 
Bahreim ; also near the coast of Java, Sumatra, &g. The 
finest and most costly .pearls are called the Oriental, and 
are from the above places ; they are all white or yellowish ; 
those from the Persian Gulf, on account of their perfect 

' whiteness, are preferred to those from Ceylon. Pearls are 
collected in rivers with the hand, but in seas it is the busi- 
ness of divers, brought up to this most dangerous occupa- 
tion from early youth. In the East Indies there are two 
seasons for pearl fishing ; the first in March and April, the 



402 A POPULAR TREATISE CN G-E^I5. 

second in August and September; and the more rain, the 
more productive are the pearl fisheries. In the beginning 
of the season there are sometimes two hundred and fifty 
barks on the banks ; the larger barks have two divers, the 
smaller, one. The divers descend from their barks with g, 
rope round their body, and a stone of twenty or thirty 
pounds attached to one of their feet, so that they may sink 
speedily from eight to twelve fathoms, where they meet 
the shells fastened to the rocks ; the nostrils and ears are 
stuffed up with cotton, and to the arm a sponge dipped in 
oil is fastened, which the diver now and then brings to his 
mouth, in order to draw breath without swallowing water. 
He also carries down with him a large net, tied to his neck 
by a long cord, the other end of which is fastened to the 
side of the vessel, to hold the shells, and the .cord is to 
draw him up when the net is full, or when he wants air ; 
he has likewise a knife or an iron rake, for detaching the 
the shells from the rocks. Thus equipped, he precipitates 
himself to the desired depth, where he can very distinctly 
see all that is passing around, yet cannot escape in time the 
sudden approach of sharks, to whom he too often becomes 
a prey. When the diver has been in water some minutes, 
and has his net filled, or is unable to stay any longer, he 
loosens quickly the stone at his foot, shakes the line, and 
he is drawn up by his companions. 'The diving-bell is now 
frequently used ; more so than in former years. 

In the Persian Gulf the divers rub their bodies with oil, 
and fasten a stone of about fifty pounds to their feet. 

The shells obtained are piled up in heaps, and left ex- 
posed to the rain and sun until the body of the animal 
putrefies, and they open of themselves. Those containing 
any pearls have from eight to twelve. After being picked 
5ut, washed, and dried, they are passed through nine sieves 
of different sizes. 



PEARLS. 403 

At the Pearl» Islands, near the Isthmus of Panama, the 
pearl fisheries have, within, a few years past, become a 
lucrative business to many of the inhabitants. The divers 
use ftiore simple methods than those we have mentioned, 
for collecting the pearl oysters : they traverse the bay in 
canoes that hold eight men, all of whom dive naked into 
the water, from eight to ten fathoms deep, where they 
remain about two minutes, during which time they collect 
all they can with their hands, and dexterously rise to 
deposit them in their canoe, repeating the operation for 
several hours. 

In Sweden, the pearl oyster is caught with a pair of 
long tongs. The fishermen are in small boats, painted 
white on the bottom, which reflects the light to a great 
depth, and as- soon as they perceive them passing under- 
neath they seize the oyster. 

Pearls are esteemed according to their size, form, color, 
and lustre ; the largest, of the size of a small walnut, are 
called paragons, which are very rare ; those the size of a 
cherry, are found more frequently, but still are rare ; they 
are the diadem or head pearls. They receive names, also, 
according to their form, whether quite round, semi-circular, 
and drum-form, or that of an ear-drop, pear, onion, or as 
they are otherwise irregularly shaped. The small pearls 
are called ounce pearls, on account of being sold by weight, 
and the very smallest, seed pearls. Those of a brilliant 
white color, or white water, are most sought for in Europe ; 
those of a yellowish color in some parts of Asia; and some 
of a lead color, or those of a jet black, are preferred among 
some nations. They all turn more or less yellow with age, 
and to restore the white color, they are either baked in 
bread, rubbed with boiled salted rice, or kept for a short 
time in the gastric juice of fresh-killed chickens. 

Pearls are sold by weight — troy weight ; but the penny- 



404 A POI'ULAR TREATISE ON GEMS. 

weight of twenty-four grains is counted as thirty ; so that 
an ounce has six hundred grains, pearl weight, and four 
troy grains are equal to five pearl grains. The price 
has, within the last forty years, much diminished, for two 
reasons : 

1st. Diamonds, and particularly brilliants, have become 
more plentiful, and have since been worn, not by the higher 
classes alone, but also by the middling. 

2d. Within the last twenty years, artificial pearls have 
been manufactured in high perfection, and are worn to a 
great extent. 

It is my opinion, however, that the price of pearls will 
take a fresh rise among the nobility and richer classes, 
diamonds being now so generally worn ; as persons, think- 
ing to invest safely, without any future loss*, -their surplus 
capital, purchase brilliants that formerly w^re possessed 
exclusively by the rich. 

Pearl fisheries were first carried on in remote times in 
the Persian Gulf, and the most celebrated, formerly, were 
near the island Bahreim. Five hundred thousand ducats 
was then the yearly produce. About one million dollars' 
worth, at the present time, are exported. The island 
Kharack now produces the most considerable quantity. 
The prmcipal market is at Muscat ; from thence they are 
brought to Surat. The mode of procuring them pursued 
in those countries, is in canoes, holding fifteen men, six of 
whom are divers: the shells caught during the day are 
delivered to a surveyor, when they are opened on a white 
cloth, and whoever finds a pearl of some value, puts it in 
his mouth, to give it, as they say, a " better water." The 
greatest harvests are generally after many rains, and the 
largest pearls are mostly found in the deepest water. At 
Ceylon the pearl fisheries are now considerable, particularly 
in the bay of Condatchy. The shells are there left to 



PEARLS. 405 

reach the age of seven or eight years, and in the fourth 
year they have small pearls, sometimes a hundred and fifty. 
They fish yearly, in the month of May, during four weeks. 
In the year 1804, eight hundred canoes, each with two 
divers, were engaged. Before the year 1800, the pearl 
banks were leased, to ah Indian merchant, for three hun- 
dred thousand pagods; and before the arrival of the Euro- 
peans in India, the same bank was used every twenty or 
twenty-four years ; when under the Portuguese, every ten, 
and under the Dutch, every six years. In 1800, the 
produce was from one hundred to one hundred and- fifty 
thousand pounds sterling. 

Japan has some, pearl banks, which are, however, not 
much sought ; the same may be said of the Nipthoa lake, in 
Chinese Tartary. America sent, in the sixteenth century, 
pearls to the amount of eight hundred thousand dollars to 
Europe. The shells were mostly collected from Cape Paria 
to Cape Velo ; round the islands Margarita, Cubagua, 
Coche Punta, Aragy, and at the mouth of Rio la Hacha, 
from which latter locality, and the Bay of Panama, Europe 
is now mostly supplied. The former- localities have long 
since been relinquished, on account of their small produce ; 
too many shells having been removed at one time, thereby 
retarding the growth of pearls. Panama has sent, within 
a few years past, about one hundred thousand dollars' 
worth of fine pearls to Euroi)e, the trade being carried on 
by Messrs. Plise, of Panama. The coast of Florida is said 
to have been very lucrative to the Indians, as a pearl 
fishery, which, however, does not prove so now, since the 
settlement of civilized people. 

England used to be supplied from the river Conway, in 
Wales ; and Scotland supplied the London market, between 
the years 1761 and 1764, to the amount of ten thousand 
pounds sterling ; but the supply has failed. Pearls are 



406 A POPULAR TREATISE ON GEMS. 

found in the Elster river, in the kingdom of Saxony, from 
its source at the borders of Bohemia to Elsterberg, where 
the iishery has been carried on since 1621, with some ad- 
vantage to the sovereign ; some pearls found there were 
valued at fifty Prussian dollars each. In the river Watawa, 
in Bohemia, and in the Moldau river, from Ktuman to 
Frauenburg, pearls are found of great beauty; so much so 
as to equal in price the Oriental pearls. Also, at Rosenberg, 
pearls are sometimes found superior to the Oriental in 
lustre ; and at Oelsnitz, a considerable pearl fishery is car- 
ried on. Most of the rivers in Sweden, Lapland, Finland, 
Poland, Norway, Jutland, Silesia, and other places, contain 
pearls, but they are not collected. 

It is a fact that the pearl is equally hard throughout all 
its concretional layers, for by putting the pearl in a weak 
acid, the outside layer becomes gelatinous, and the suc- 
ceeding layers are found to be equally hard and uniform. 
It is almost impossible, therefore, that the story told of 
Cleopatra having swallowed a pearl after being dissolved 
in vinegar, should be true ; besides, if the pearl had been 
dissolved as quickly as reported, it would not have made 
a very disagreeable beverage. Pearls were known, and 
were very much esteemed by the Greeks and Romans, and 
when they became acquainted with th§ Indies, by com- 
mercial intercourse and conquest, they preferred the pearls 
of the East to those that were obtained from the rivers of 
Europe, or even from the Mediterranean. 

With the ancients the wearing of this species of curiosity 
became a passion and even a folly. Necklaces, bracelets, 
and ear-rings were then worn in profusion ; dresses, head 
and foot ornaments were manufactured with pearls. Mil- 
lions of sesterces (a Roman coin of two hundred francs 
value), were expended and lavished for the best and most 
extraordinary pearls. The two pearls of Cleopatra cost 



PEARLS. 407 

nearly two in-illions of francs ; Julius Caesar presented to 
Servilia, the sister of the celebrated Cato, of Utica, a pearl 
which he pui'chased for one million two hundred thousand 
francs. 

Lollia Paulina, the wife of Caligula, wore ornaments to 
the value of eight millions of francs. The ladies went so 
far as to ornament their buskins with pearls. Nero lav- 
ished pearls upon his lewd women. In modern times 
Buckingham distributed in the halls of the Empress Ann, 
of Austria, and of King Louis XIII., pearls to the value of 
three hundred thousand francs. 

The baroques, w^hich are excrescences in the mother of 
pearl, are sometimes very large, and display some extraor- 
dinary figures and inconceivable freaks of nature. They 
are held in high estimation, and are mostly worn in Spain 
and Poland. 

Caire, the celebrated French jeweller, possesses many 
baroques ; one representing a bearded dog ; another, rep- 
resenting^ the order of the fleece. He had a mother of 
pearl containing a large excrescence, representing a Chinese 
with crossed legs. 

• The prices of pearls, from one carat upwards, were for- 
merly determined like those of diaaiionds, viz : if the carat 
'be fixed at five dollars, and a pearl w^eighs four carats, take 
the square, or sixteen, which multiplied by five is equal to 
eighty ; so that a pearl of four carats was estimated at 
eighty dollars. 

At present the following are the prices of pearls : 
1 grain is worth, in France, 4 francs per carat. - 

9 u u u 20 " " 

3 " " " 25 " " 

4 " (1 carat) " 50 " " 

The baroque pearls are sold at from three hundred to 
one thousand francs per ounce. 



408 A POPULAR TREATISE ON GEMS. 

The seed pearls, when quite round, are worth about one 
hundred and twenty francs per ounce. 

In France, perforated * pearls are valued at twice the 
prices given above. The piercing of the pearl is well un- 
derstood " in the Indies. The value of a pearl is always 
enhanced by size, perfection, and color ; those that have a 
yellowish-Avhite, or silver-white, or very pale gold-yellow 
shade, or a rose or lilac color, are the most esteemed 
pearls. 

The French pearl fisheries produce at least from three to 
four millions of francs. 

The French Crown possesses pearls of immense value : 

One round virgin pearl, of a magnificent orient, weighing, 
27i\ carats, is valued at two hundred thousand francs. Two 
pear-shaped pearls, well formed, of a beautiful orient, and 
weighing together 57j^ carats, are valued at three hundred 
thousand francs; two ear-drops, weighing 99j-^g- carats, are 
valued at sixty-four thousand francs. 

About seventy-two more large pearls, of great beauty 
and exquisite form, pear-shaped and round, valued in the 
aggregate sum of three hundred and fifty thousand francs. 

At the Paris Exhibition, in 1855, an enormous pearl, of 
pear-shape, brought from Berlin, by Napoleon I,, was 
exhibited. 

The Princess Royal of England, at her marriage to 
Prince Frederic William, of Prussia, wore a necklace of 
the finest pearls, which cost, at the. least calculation, five 
hundred thousand Irancs. 

The Emperor Rudolph possessed a pearl weighing one 
hundred and twenty grains. 

King Philip II., of Spain, possessed a pear-shaped pearl 
of the size of a pigeon's egg, weighing one hundred and 
thirty-four grains. It came from Panama, and was valued 
at fifty thousand ducats. It was called the Peregrina. 



PEARLS. 409 

« 

In 1620, King Philip lY"., of Spain, purchased a pear- 
shaped pearl from Gougitas, of Calais, which weighed four 
hundred and eighty grains. An anecdote is told of the 
King, who asked the merchant how he could risk his whole 
fortune in so small a piece as that pearl ; whereupon the 
merchant replied, that he knew there was one king of 
Spain in the world who could afford to purchase it. It 
now belongs to the Princess Youssopoff. 

A costly collection of pearls from the Indies, Ceylon, 
and Singapore, and innumerable pieces of ornamental jew- 
elry set with most costly pearls, was exhibited at the Lon- 
don Exhibition by Messrs. Garrard, Hunt, Roskell, and 
other jewellers. 

A large pearl, from Vermont, United States, weighing 
eleven carats, and very round, but not of bright color, is 
in the possession of Mr. S. H. Palmer. 

Messrs. Blogg &; Martin, of London, inform me, under 
date of April 25, 1859, that they have in their possession a 
magnificent pearl necklace, consisting of thirty-seven per- 
fect pearls, of forty grains each ; they sent a description of 
it, and also of two beautiful pearl-drops, which they value 
at two thousand pounds sterling. The necklace and drops, 
which must be unique specimens, deserve more tban a 
mere notice, but the description came too late for insertion. 

Ignited States Pearls. 

New Jersey merits the credit of producing fine pearls ; 
a great many thousand pearls have been obtained from the 
mussels, which compare fairly with those of the India pearl- 
shell ; size, color, nacre, and orient are displayed in many 
of the New Jersey pearls in a high degree, and are now 
passing in E.urope for the genuine Oriental or Panama 
pearls. In IBS'?, a shoemaker named David Howell, living 

18 . ' 



410 



A POPULAR TREATISE ON GEMS. 




Fig. 12 a. 





Fig. 13. 



Fig. 14. 



PEARLS. 



411 




Fig. 12 I. 





Fig. 15. 



Fig. 16. 



412 A POPULAR TREATISE ON GEMS. 

near the town of P.aterson, New Jersey, went to a neighbor- 
ing brook, called Notch brook, in order to collect some 
mussels for his breakfast, and, on opening th^, discovered 
a gr?at many loose pearls falling out, which he took to a 
jeweller in Paterson, who stated to him that they were 
valuable, and they both began to collect millions of these 
mussels, and their efforts were crowned with success. The 
preceding representation of the mussel belongs to the great 
family of unio, which was formerly called the avicula mar- 
garitifera, mya margaritifera, but now known as an alas- 
madonta arcuata — named by Barnes. Many unios (of 
which there are, according to Lea, Say, and other Ameri- 
can conchologists, over six hundred species), contain pearls 
more or less ; and Mr. John H. Redfield, the efficient 
corresponding secretary of the New York Lyceum of 
Natural History, informs me that he found the pearls in 
the same locality in New Jersey, in three or four other 
unios, such as the unio complanatus, unio ochraceus, unio 
radiatus, &c. A very perfect pearl in the shell may be 
seen in the annexed drawing, which is copied from " Frank 
Leslie's Illustrated News" of May, 1857; the pearl is rather 
dark, and the shell, as may be seen, appears worn oif. 
This is one of the characteristics of the shells containing 
pearls, and it appears to indicate that the animal is in the 
decline of life, and that the mussel is becoming gradually 
decayed. 

r The streams in which these pearl shells are found are 
generally very shallow, not more than one or two feet 
deep, and the shells may be picked up with the hands; 
many thousand shells are opened, containing deposits of 
the pearly matter, most of which contains shapeless and 
colorless pearls, which are so small that they are of no 
value ; many, however, contain very perfect pearls ; the 
crown-pearl, weighing ninety-one grains, in the possession 



PEAELS. 413 

of Messrs. Tiffany & Co., was purchased from Mr. Howell 
for $1500. This pearl resembles a crown, having three 
smaller pearls resting upon the large pearl ; another repre- 
sentation of a pearl weighing nearly four hundred grains, 
here represented, was destroyed by cooking the mussel in 
order to open it better, and the color of the nacre has 
been spoiled ; it would, probably, have been the largest 
pearl of modern times, and of immense value. 

The alasmadonta of the present day was formerly called 
mya, from the Greek .fivo), to compress, it is called in 
English, the gaper, on account of the bivalve gaping at one 
end, its hinge having a solid, thick, patulous tooth, seldom 
two, and not inserted in the opposite valve; the same 
genus was originally called mytilus; they inhabit both 
the ocean and fresh water; they perforate the sand or 
mud at the bottom. Many species are caught for food, 
and others for the pearls; some few of the same genus 
perforate and live in limestone, like the pholadites. 

The pearl-beaving mya, now alasmadonta, is frequently 
found in the large rivers of northern latitudes. The Brit- 
ish Islands, especially Ireland, were formerly .famous for 
their fisheries, and a few pearls of great value have at times 
been obtained from these sources, although the British 
specimens are not held in high estimation, with the excep- 
tion of a few procured from the river Shannon, in the 
year 1821. 

The river Irt, in Cumberland, the Conway, in Wales, 
and the Tay, in Scotland, were once noted for their pearl 
fisheries. Suetonius reports that Caesar was induced to 
undertake his British expedition for the sake of the pearls ; 
and according to Pliny and Tacitus, he brought home a 
. buckler made with British pearls, which he dedicated to, 
and hung up in the temple of the idol Yenus genetrix. 

The gapers are mostly used for food, both in Britain 



414 A POPULAR TREATISE ON GEMS. 

and on the Continent ; around Southampton, in England, 
these mussels are known by the whimsical name of " old 
maids," and the inhabitants of the northern islands call 
them smuslin, and consider it a fine supper-dish, which is 
by no means unpalatable.* 

I am informed by Mr. Plise, who brought a considera- 
ble quantity of pearls from Panama, that he receives four 
dollars per grain in England, for those of good size and 
quality. 

Pope Leo bought a pearl for eighty thousand crowns. 
Tavernier describes one belonging to the King of Persia, 
which is said to have cost one million six hundred thousand 
livres. Portugal has a pearl in her treasury of the size of 
a pear. Two" Greeks, residing in Moscow, are in posses- 
sion of a pearl weighing twenty-s&ven and seven eighths 
carats. 

For restoring Oriental pearls to their original lustre, 
which they lose in the course of time, the following pro- 
cess is resorted to in Ceylon : the pearls are allowed to be 
swallowed by chickens, which are then killed, S,nd the 
pearls are an hour afterwards taken out of the stomach, 
when they are as white and as lustry as if just taken from 
the shell. 



* The poet Cowper thus expatiates on the mussel : 
" Condemn'd to dwell 
Forever in his native cell ; 
Ordaiii'd to move where others please, 
Not for his own content or ease ; 
But toss'd and buffeted about, 
Now in the water and now out ; 
Yet in his grotto-work inclosed 
He nothing feels in that rough coat, 
Save when the knife is at his throat; 
Wherever driven by wind or tide. 
Exempt from every ill beside." 



PEAELS. 415 

, Artificial Pearls. 

Artificial pearls or beads are of various kinds ; most 
generally they consist of solid masses of glass, with a hole 
drilled in them ; or they are blown hollow, and then filled 
out with metallic lustry grains, wax, or with the fine scales 
of the. bleak fish, which have a silvery and pearly lustre. 

The art of imitating pearls is attributed to a manufac- 
tu]*er of beads, of the name of Janin or Jalquin, who lived 
at Paris in 1680; he was led to the discovery by seeing, 
one day, the scales of the bleak fish swimming in a trough, 
where the fish detached them by rubbing against each 
other, and he at once conceived the idea of applying these 
scales for imitating the orient of the pearls, by mixing 
them with a mucilage and filling the interior of hollow 
glass bulbs, and he gave this natural and wonderful pro- 
duQtion the name of Extract of Orient — a very singular 
name, but still significant of the rgeaning of its employment. 
It is well known that this little white fish, the bleak, is 
found in abuMance in the rivers Seine and Marne, in 
France, and in many small rivers in Sweden, Germany, 
and Italy. The bleak fish fructifies around water-mills, 
where they are caught by nets. 

For the purpose of extracting the color of the scales of 
the fish, they are rubbed pretty hard in the fresh water 
collected in a stone basin, which settles down in the bottom 
of this vessel ; the sediment is then pressed out through 
a linen rag, and they are then replaced again in fresh 
v/ater and left there to settle for several days, when the 
water is drawm off and the precipitate is carefully collected ; 
this is called the extract or essence, and it requires from 
seventeen to eighteen thousand fishes to obtain five hun- 
dred grammes (a little over one pound). 

The scales being animal matter are, therefore, liable to 



416 A POPULAR TREATISE ON GEMS. 

decomposition, and for their preservation numerous chemi- 
cal agents have been employed by the different manufac- 
turers, all of whom, who have succeeded, keep it a secret ; 
it is, however, known that liquid ammonia is added to the 
paste of the scales. • 

The operation of the manufacture is very difficult, but 
an experienced workman can manufacture six thousand 
pearls in a day. 

The chemists have experimented for some years to imi- 
tate the extract of orient, — as it requires such a large 
quantity of fishes to obtain any amount of the scales, — and 
according to Mr. Barbot, the following preparation has 
produced a favorable result : which is by distilling one part 
of oxide of bismuth and two j^arts of corrosive sublimate ; 
the product is a species of butter, which on redistilling 
yields metallic quicksilver and a very fine powder ; this is 
the substance used for orientalizing or coating the artificial 
pearls with the true gloss ^f an Oriental pearl. 

The same scales are likewise used to coat beads of gyp- 
sum, or alabaster, which are soaked in oil and then covered 
Avith wax to give them a pearly appearance. The Roman 
beads are made in this manner : the scales are dissolved 
either in liquid ammonia, or vinegar, and the solution or 
liquid is used for covering those artificial beads. The Turk- 
ish rose-beads are made of an odoriferous paste, and are 
turned afterwards like those of coral, amber, agate, or 
other 'hard substances. The knitting beads are sold in 
meshes of one hundred and fifty, or twenty strings, of 
fifty beads each, of various colors ; and the large glass- 
beads in meshes of twelve strings. There are numerous 
manufactories in Germany and Italy of the various kinds 
of beads, which are used to a very great extent both in 
Africa and North and South America. Germany exports 
yearly from its different manufacturing places, such as 



PEAELS. 417 

Heidelberg, Nuremberg, Sonnenberg, Meistersdorf, in Bo- 
hemia, and Mayence, more than a million dollars' worth. 
In Venice are large establishments for the finest cut beads. 

Nuremberg manufactures, besides glass beads, consid- 
erable quantities of amber beads. In Gablontz, in Bohe- 
mia, more than six thousand persons are engaged in the 
manufacture of beads, that are made of pure glass, or of a 
composition. From the glass-hou-ses, which are very- 
numerous in Bohemia, the rods of different sizes are 
delivered to the glass mills for cutting, which is performed 
by water power or by hand. In 1828 there were in that 
neighborhood one hundred and fifty-two mills in operation ; 
a number of glass-blowers were likewise engaged, w^ho 
possessed great dexterity in blowing the small beads with 
the assistance of a small blow-table. In the manufactory of 
George Benedict Barbaria, at Venice, six hundred varieties 
of beads are constantly making ; and that of Messrs. Gas- 
pari and Moravia manufactures, besides the beads, every 
article of jewelry from the same material. 

The rose beads of Steffansky and Tausig, are made of 
bread crumbs, w^hich are beaten up with rose water in a 
wooden mortar, until they become a uniform mass, to 
which is added some otto of roses and drop-lake, when it is 
made into beads with dissolved gum tragacanth-; for the 
black rose-beads, Frankford black is substituted in the 
place of the drop-lake. 

Lamaire, of France, manufactures beads equal in lustre 
an^ beauty to real pearls. He adds to 
1000 ounces of glass beads, 

3 " scales of the bleak-fish, 

i " """■ fine parchment glue, 
1 " white wax, 

1 " pulverized alabaster, 

with which he gives them an external coating. 

18* 



418 A POPULAR TREATISE ON GEMS. 

Rouyer manufactures his beads, also in France, from 
opal, which he covers with four or five layers of dissolved 
isinglass, and then with a mixture of a fat oil, spirits of 
turpentine, and copal, so as to prevent their becoming 
moist. In order to render them of the peculiar lustre of 
the Oriental pearls, they are covered with a colored enamel. 
The opal is fused into rods by a lamp, over which is laid a 
brass wire to support it ; the wire is held in one hand and 
the opal in the other, and the wire is then kept turning 
until the bead has the desired size and roundness ; if a 
colored enamel is to be applied, the beads are made but 
half the required, size, which being done, they are once 
more covered with the opal, then the solution of isinglass 
is used, and lastly the varnish. Beads made in this man- 
ner are with difficulty distinguished from the Oriental 
pearls. 

The best method of making artificial pearls, is certainly 
by means of pulverized real pearls. • Either the smallest, or * 
the deformed large specimens, may be reduced to a fine 
powder, and then soaked in vinegar or lemon-juice, and 
the paste made up with gum tragacanth ; they may then be 
cut out with a pill machine, or a silver mould, of any desired 
size, and when a little dry, inclosed in a loaf and. baked in 
an oven : by tin amalgam, or by the silver of the scales of 
young fish, the proper lustre may be given. 

The artificial pearls, by Constant Vales & E. Truchy, of 
Paris, which were on exhibition in the London Crystal 
Palace, were extremely beautiful, and were with ^the 
greatest difficulty distinguished from the natural pearls. 

Messrs. Bouillette, Hyvelei & Co., of Paris, exhibited, 
besides many beautiful pearls, a great variety of artificial ' 
stones, all of their own manufacture, and very tastefully 
set ; among them was a stomacher in diamonds, pearls, and 
emeralds. 



COKALS. 419 

The shad-fish, as well as the white-fish of our lakes, must 
yield an extract of orient, of as good a quality as the bleak- 
jSsh of the Seine, and it is to be hoped that some enter- 
prising mechanic may take an opportunity of preparing the 
white matter adhering to the scales of the fish just men- 
tioned, either for export, or for the purpose of imitating 
pearls, which may be done as well in this country as any- 
where else. 

The usual price of false pearls is two dollars and fiftjt 
cents a string, — one hundred to the string; but some are 
lower, and some higher, according to color. 

CORALS. 

Corals are zoophytes, whose calcareous habitations resem- 
ble vegetable branches. They live in the sea, adhering to 
rocks, stones, or vegetables, and shoot to the surface of the 
water in tubiform stems with branches, generally coated 
with a gelatinous or leathery skin that incloses a cartilagi- 
nous marrow, composed of many cells, inhabited by the 
animals, — who propagate in sprouts from eggs so fast, that 
small reef-rocks are formed, which in the course of time 
become islands. 

The red coral, or precious coral (iris ?ioMlis), belongs to 
that family of zoophytes which live mostly in the cavities 
of rocks in the sea; the stem is always of a beautiful red 
color, rarely white ; quite compact, striated on the outside, 
of entire calcareous composition ; it grows one foot high 
and an inch thick. The stem is covered with a leathery 
crust, containing open warts of eight teeth, in which the 
animals, or polypi, with their eight arms, are situated ; the 
arms are whimpered, and the animal grows very slowly. 

The red coral is fished up with nets of strong ropes, fas- 
tened on large wooden cross-beams, which are thrown 



420 A POPULAE TREATISE ON GEMS. 

down on the places where the corals are known to be fas- 
tened, and an expert diver contrives to entangle the nets 
in the reefs, which are then drawn up by force. The corals 
so brought up are cleaned, assorted, and sold to the manu- 
facturers. 

Messrs. Payenne & Laminal have invented a very inge- 
nious machine for collecting the coral from the banks of 
the ocean, without breaking the fine branches and without 
injuring the banks which are formed for the growth of the 
coral. 

It is a fact admitted by naturalists and fishermen, that 
the growth and accumulation of tl^ zoophytes take place 
continually in the same waters ; and that as great and pro- 
lific a trafiic may be created by coral catching as by the fish- 
eries in France. Lord Ellis proved, in 1754, that the coral 
polype possesses an ovarium filled- with small eggs, pre- 
pared for hatching ; all these eggs are attached together 
by a species of cordon, and resemble worms ; tentacles are 
shooting out from them, which move in the same manner 
as the grown polypes. 

In 1856, Mr. Focillon presented a report to the Acclimi- 
tation Society at Paris, on the methodical exjDloration of 
the ancient and natural banks, and on the construction of 
artificial coral banks in such a manner as to secure the 
most favorable position for the production and operation 
of an easy and sure coral harvest. Facts have already 
been elicited, that the new coral succeeds so well at a 
depth of seven to eight metres (twenty-four feet)., under 
the influence of the rays of the sun, that it develops quickly, 
and becomes large and of good color at the end of eight or 
nine years ; while a coral at a depth of thirty to fifty 
metres (one hundred and fifty feet), requires from thirty- 
five to forty years to shoot out, and it is not then of as 
good a color as the former. This discovery ought to 



CORALS. 421 

stimulate the African coast (Algeria), particularly the in- 
habitants on the shores of Bona, Oran, and other places, 
who ought to be beforehand in the application ; also on the 
Marseilles coast, which is already full of coral reefs. 

Coral was formerly cut in facets, and was in great favor 
under the consulate and empire of France, for almost every 
species of luxury ; combs, ear-rings, necklaces,* beads, 
crosses, &c., were manufactured and sold at high piices ; but 
the fashion and price soon fell. Ten or jfifteen years after- 
wards an endeavor was made to bring coral in vogue again, 
by offering coral engraved as cameo, and made into other 
ornaments, — such as brooches, bracelets, ear-rings, and pins, 
which were then sold pretty high ; but on account of an 
insufficient supply of the article and bad workmanship, it 
fell back to its original lethargy, and for many years it was 
considered worthless and altogether out of fashion. 

During the last two years, coral has resuscitated very 
much, and got into good grace wdth the ladies. 

The Parisians have, however, changed their taste for the 
former favorite, — the red coral ; the rose-colored^ cut in a 
round form, so as to nearly resemble a rose pearl, being 
preferred, which is acknowledged to be extremely rare. 
The price of these rose-colored corals has of late risen so 
high, that a fabulous sum is paid for them ; and a coral 
which was worth but fifty francs in 1810, is now sold for 
three hundred francs and upwards. At present the fashion 
for corals is at its height, and ornaments of every con- 
ceivable variety may be seen in the shops of jewellers in 
this country, imported from France and Italy. 

At the last Paris Exhibition there was a coral chess- 
board, with all its figures representing an array of Cru- 
saders and of Saracens, which was admirably executed, and 
valued at 10,000 francs. Coral branches, if without a frac- 
ture, bring a great price. 



422 A POPULAR TREATISE ON GEMS. 

France manufactures and exports coral ornaments to the 
value of six millions of francs, and the demand for them 
is much greater ; the establishments of Barbaroux and 
Garaudy & Fils, in Marseilles, where the coral is principally 
manufactured into ornaments, give proof that France will 
retain the supremacy in this species of luxury. 

In the Paris Exhibition of 1855, many curious sculptured 
and chiselled objects were shown by Arsene Gourdin, of 
Paris. 

In the London Exhibition, fine corals were shown from 
the Cape of Good Hope, from Reffaelli & Son, in Tuscany; 
from Algiers was also a collection. Tucker & Co., of Ber- 
muda, exhibited a fine collection of both corals and madre- 
pores, including the black flexible coral (gorgonia). 
Among the ancient rare coral engravings is the Jiead of 
the philosopher, Chrysippe, in high relief: it was in the 
Orleans collection. A coral cameo of the 14th or 15th 
century, representing a Sphinx with three Cupids, well 
executed, is mentioned by Caire. 

The red corals are distinguished by the names of the 
countries where found. 
^ 1. The Barbarian, Avhich are the thickest and purest. 

2. The Corsican, which are the darkest, but not so thick, 

and less pure. 

3. The Neapolitan, and those from Ponza, which are 

clear and pretty thick. 

4. The Sardinian, which are thick and clear. 

5. The Catalonian, which are nearly as dark as the Cor- 

sican, but mostly thin. 

6. The Trapanian corals, from Ti'apani, in Sicily, which 

are somewhat preferred at Leghorn. 
The darkest corals are most liable to be worm-eaten. 
The polished corals are generally sold in bundles, which 
consist of a certain quantity of strings;, of a certain weight. 



COEALS. 423 

They are strung in Leghorn, either of various or equal 
thicknesses, which latter are then of various sizes, and the 
bundles receive their names accordingly ; grossezze,, mez- 
zanie^ filotti^ capirest% &c. The thickest corals are put s 
up in one string, resembling a tail, and are called coclmi j 
the smallest are called s^nezzati. 

At Genoa, the various large corals are called mezza- 
nie ; the uniform large, filze ; and the uniform small, 
migliari. 

They are distinguished according to color at Leghorn ; 
the darkest red are called arcispiuma^ which are the dearest ; 
and then primo^ secxtyido^ terzo^ quarto^ coloro or sangiie^ 
chiari^ moro^ nero^ &c. 

According to form they are called round {tondi)^ and 
cylindrical-round {hoticelli). The former are sent to all 
parts of the world, but the latter are only sent to Poland. 
The large hoticelli are put up in meshes of twelve pounds, 
containing thirty-six strings ; and the middling size of the 
hoticelli are in meshes of six pounds, containing sixty 
strings ; those hoticelli which are still larger, are called 
olivatti^ and are only sent to Africa ; those which are glob- 
ular, and not drilled, are called pallini altorni^ and sent 
principally to China, where the favorite color is the rose- 
red. 

The sound corals are called netti^ and the worm-eaten, 
camolatti^ which latter are mostly sent to the East Indies. 
The tops of the branches are called dog-teeth^ or dents 
canines^ and the thick ends of the branches are called mao- 
metti ; both kinds are perforated lengthwise, and are used 
in Barbary as ornaments for horses. The fine large coral 
stems which form suitable specimens for cabinets of natural 
history, in Marseilles, are called chouettes. 

There are one hundred varieties of shades of red coral 
distinguished at Marseilles. 



124 A POPULAR TREATISE ON GEMS. 

Corals are principally used for ornaments, in the East 
Indies, China, and Africa, where they are preferred to the 
diamond. Almost every East India lady wears a bracelet 
or necklace of corals. 

The white coral has its origin from the eight-star coral 
{inadrepora occulta); and the black coral from the black- 
horned coral {gorgonia antipothes). The medusa head 
{caput medusae)^ called the sea polen, belongs likewise to 
the coi-al family, and consists of sixty-two thousand six hun- 
dred and sixty-six articulated members. 

Corals are fished for on the coast of Barbary, between 
Tunis and Algiers ; in the latter state Bona is the principal 
station ; the French have one also at Basteon de France. 

The monopoly was purchased by France, in the seven- 
teenth century, at eighteen thousand dollars annually; and 
by England, since 1806, for fifty thousand dollars. 

At Bona there is a summer fishery, from the fii'st of 
April to the first of October, which occupied, in 1821, 
thirty French, seventy Sardinian, thirty-nine Tuscanian, 
eighty-three Neapolitan, nineteen Sicilian barks ; alto- 
gether, two hundred barks of two thousand and twenty- 
three tons capacity, with two thousand two hundred and 
seventy-four men ; they fished up forty-four thousand two 
hundred pounds of coral, valued at two million four hun- 
dred thousand francs. The winter fishery of the same year 
occupied three French barks, each with nine men, and they 
obtained six hundred and eighty pounds of coral. 

The principal manufactories of corals are now at Leg- 
horn, where this branch of business has been carried on for 
two hundred years past, by the Jews. There were for- 
merly twenty establishments, but the number has lately 
been much diminished. 

They are sent principally to China, the East Indies, and 
Arabia, partly by the way of London, and partly by Mos- 



SHELL CAMEOS. 425 

COW, Aleppo, and Alexandria; many corals are likewise 
sent to Poland. 

Genoa has a few manufactories, in which the Sardinian 
corals are mostly wrought. At Marseilles there has been 
a large manufactory ever since 1780, and at present it is 
the only establishment of the kind in France. 

The East Indies consume, according to the statement of 
Le Goux de Haix, nearly four million francs' worth. 

Corals are worn in the East as ornaments in the turban, 
and the Arabs bury the coral with their dead. 

A large coral, from the manufactory* at Marseilles, was 
sold in China, to a mandarin, for twenty thousand dollars. 

Purpurin is the name of artificial coral. A large quan- 
tity of this false and base imitation of coral has been im- 
ported into this country. It is used for setting in cheap 
jewelry; brooches, bracelets, ear-rings, and pins may be 
seen everywhere in this city, all carved in figures and ani- 
mals, resembling the true coral, but on testing it with a 
knife, the baseness is easily detected. It is composed of 
marble powder, made into a paste by a very siccative oil 
or varnish, or soluble glass (silicate of potash), and a little 
isinglass, and colored by Chinese vermilion. The paste 
is then moulded into the various objects required, and when 
dry such parts as require it are perfected with the chisel. 

SHELL CAMEOS. 

• 

The shells employed for cameo-cutting, are the cassis 
rufa, and several species of cyprea, called cowries. They 
are dense, thick, and consist of three layers of differently 
colored shell material. In the cassis rufa, each layer is 
composed of many very thin plates, or laminae, which are 
perpendicular to the plane of the main layer ; each lamina 
consists of a series of elongated prismatic cells, adherent by 



426 A POPULAR TREATISE ON GEMS. 

their long sides ; the laminae of the outer and inner layers 
are parallel to the lines of growth, while those of the 
middle layer are at right angles to them. ' In cowries 
there is an additional layer, which is a duplicature of the 
nacreous layer, formed when the animal has attained its 
full growth. 

At the London Exhibition there was a very fine collec- 
tion of shell cameos, from Rome, owned by the engraver 
Seculine. 

Certain natives of India prepare shell cameos with rude 
but efficient instruments for cutting them, and the Indian 
(department in the Exhibition showed numerous specimens. 

MOSAIC AND PIETRA DURA. 

Roman^ Venetian^ Florentine^ and other Mosaics. — 
The art of mosaic {opus musivum of the Romans), was origi- 
nally applied only to the combination of small dice-shaped 
stones (precious and common), or tesserae of the ancients, 
in patterns. It has long been an important source of labor 
to the inhabitants of several parts of Italy, such as Venice; 
and under various modifications is now carried on in the 
principal cities of Europe; The manufacture has long 
ceased to be confined to combinations of tesserae, and is 
now understood to include all kinds of inlaid and veneered 
work, in whatever material, — fragments of pseudo-precious 
stones, (agate, chalcedony, malachite, lapis lazuli), marbles 
of the most variegated colors, porphyry, lava, granite, 
fluor-spar, and also the various colored glasses (imitation 
gems), avanturine, and enamels, which, when put together 
(sometimes in microscopical fragments), and formed into a 
landscape, figures, or other design, are now called mosaics. 
The richer the colors and shadings, so as to produce fine 
pictures, the more striking the mosaics fall on the eye of 



MOSAIC AND PIETEA DUEA. 427 

the spectator. The Roman mosaics, in which prisms or 
threads of glass, of various sizes and shapes, compose the 
whole picture ; the Venetian mosaics, where the glass is a 
tessera or square shape, of some size, inlaid often in a 
cement base. 

The manufacture of true Roman mosaics has always 
been confined to the city whence its name is taken, and no 
country has entered into competition with Rome. They 
are composed of glass, sometimes called smalt, and some- 
times paste ; are made of all kinds of colors and every 
different hue. For large pictures they take the form of 
small cakes; for small works they are produced in threads, 
varying- in thickness from that of a piece of string to the 
finest cotton thread : large quantities of these, of all tints 
and colors, are prepared. A plate or slab of copper, marble, 
or slate is then provided, of the size and thickness required 
for the intended work. This slab is hollowed out so as to 
resemble the bottom of a box or a tray, to a depth propor- 
tioned to the work; this may vary from an inch to the 
eighth, or even the sixteenth of an inch, if the work is to be 
small. This hollow is then filled with plaster of Paris, w^ell 
smoothed, on which the outline of the proposed design is 
very accurately traced, and an inked pen is passed over 
the outline to preserve it. Yery few tools are required by 
^the workmen, but for the large works, where comparatively 
large pieces are to be inserted, small shape-cutting ham-' 
mers arfe made use of for splitting the cakes and reducing 
them to their proper size and form ; pincers also, of differ- 
ent forms, are used for placing them equally. In very 
small works, instead of hammers, sharp-pointed pincers are 
made use of, like thosfe with which diamonds are taken up, 
and sometimes a small tool like a scarpellb. The heat of 
an oil lamp is required, to enable the workman to draw out 
the strips of glass to the desired fineness, even to that of 



428 A POPULAR TREATISE OX GEMS. 

a liair. When this is all ready, the first operation is to dig 
or scoop out, with a scarpello of a proper size, a snaall piece 
of plaster of Paris from the bottom of the box or tray, 
without injuring the outline ; this is filled up with a kind 
of mastic or putty, like that which is used for panes of 
glass in the sashes of a window ; and the required piece of 
smalt or glass is then pressed into the composition. In this 
way, step by step, and from day to day, repeating the 
operation of scooping out a small piece of plaster of Paris, 
and never losing sight of the outUnes, they gradually fill 
up the whole tray. In works of considerable dimensions, 
the workmen place th€ tray before them as painters place 
the canvas on which they are painting, and have the origi- 
nal always close to them. For smaller works they sit at a 
table, as if writing, and keep the work flat on the same. 
The designs used in these mosaics are for the most part 
copied from the pictures of some artist of eminence, the 
designers themselves being also a separate body, working 
for the niosaicisti^ who mechanically fill up the spaces as 
above described. When the operation is completed, it is 
passed over a stone made perfectly smooth and cleaned of 
every kind of dirt ; it happens, however, that interstices, 
however minute, will be left more or less between the 
several small pieces of smalt inserted into the mastic ; these 
are to be carefully filled up with heated wax, applied with 
hot iron instruments from a pallet on which it has been 
prepared for the purpose, and much of the good eflect and 
finish of the work will depend on the ability and care of 
the workmen by whom this operation is performed. 

A most remarkable specimen of this beautiful art was 
shown at the London Exhibition, by the Cavaliere Bar- 
beri ; it was a large round table, and represented cele- 
brated views in Italy; it was of singular delicacy and 
beauty of workmanship, — the style of the design, the ex- 



MOSAIC AN^D PIETRA DUE A. 429 

quisite shading of the colors, the brilliant though softened 
effect of the group of views, the atmosphere and sky of each 
mingling into the same ethereal tint, which relieved the eye 
and allowed it tO rest with pleasure on the separate views : 
it was certainly a masterpiece. The author never left the 
Crystal. Pal ace without passing by the table, which always 
excited fresh admiration. 

There were two other mosaics, 'much larger than the 
former, and different in style, that were remarkably fine 
specimens of workmanship : one was a, copy of a celebrated 
picture, by Guercino, — a St. John the Baptist ; and the 
other a portrait of Pope Boniface the Second. 

A circular table, a square slab, and a picture represent- 
ing a view of Psestum, were likewise among the Roman 
mosaics in the London Exhibition. 

Dr. Chilton, of New York, has a beautiful Roman 
mosaic of the Pantheon, about three inches long. 

In the New York Exhibition, in 1853, the large pic- 
ture of Pope Pio IX., in medallion size, was much ad- 
mired. 

In the Paris Exhibition, in 1855, many large works of 
Roman mosaics were exhibited ; one in particular, belong- 
ing to the Duke of Tuscany, required the constant work 
of fourteen years, and -cost 700,000 francs. A large table 
in the rotunda of the panorama, of rich and elegant Roman 
mosaic, cost 400,000 francs. 

The famous picture of the Campo-viacino^ in Rome, by 
Galand, cost the artist ten years' labor. 

Pietra dura^ also called Florentine mosaic^ consists in 
the manufacture of hard stone inlaid in a slab of marble ; 
they are, for the most part, of the quartz species, such as 
agates, jasper, chalcedony, carnelian, &c. ; also, lapis lazuli, 
malachite, and all such hard and colored minerals which, 
by their depth of color and brilliancy of lustre largely con- 



430 A POPULAR TREATISE OX GEMS. 

tribute to produce a picture of a flower or a landscape, and 
all come utider the name pietra dura of the Florentine 
school. 

In this kind of work, a slab of marble (generally black), 
of the required dimensions, and about one eighth to three 
sixteenths of an inch thick, is prepared, and the patterns to 
be inlaid are carefully cut out with a saw and file. The 
hard stones are worked into the required pattern by the 
ordinary methods of gem-cutting, and are accurately fitted 
into the spaces thi^g prepared, in a polished and finished 
state ; for if the whole were to be polished at once, some 
of the substances being softer than others, would be worn 
away too rapidly. The work, also, is liable to be spoiled 
by the accidental placing of one stone lower than another, 
and mistakes of this kind will often lead to the ruin of the 
whole. After the surface is thus prepared it is veneered 
on a thicker slab and is then fit for use. In point of diffi- 
culty of execution, durability, and taste, this process of 
inlaying in hard stones or gems may rank as the most im- 
portant purely decorative work within the whole range of- 
mineral manufactures. 

In order to illustrate the peculiar mode of inserting the 
different pieces of agate, jasper, &c., in these beautiful 
works of art, and to show also to those not familiar with 
them the elegant and simple forms produced, we give the 
following diagram, showing a fac-simile of a portion of 
the inlaid-work in one of the tables which were exhibited 
in the London World's Exhibition, in 1851. • 

In this diagram the dark line represents the outline of 
the flowers, leaves, &c., and the dotted part, the lines 
where the different pieces forming a single object are 
joined together. The extreme delicacy and accuracy of 
the joints can only be fully appreciated by the examination 
of the original specimens. 



MOSAIC AND PIETRA DUEA. 



431 




Fig. 11. 

True Florentine mosaic, of fine design and good taste, 
was in profusion from Tuscany and St. Petersburg. 

A jewel-case belonging to the Empress of Russia, was 
particularly worthy of notice : it was constructed of wood, 
having the four sides and top covered with groups of fruit 
cut in pietra dura^ in a style which may be called cameo- 
mosaic in rather high relief; the stones were so- selected as 
to afford perfect fac-similes, in color, size, and even in in- 
ternal structure, of the fruit they represented, which were 
cun-ants, pears, and plums, and the whole work was ex- 
quisitely finished. 

The King of Sweden sent to the London Exhibition, 



432 A POPULAR TREATISE ON GEMS. 

an inlaid oblong table of granite, porphyry, and jasper, 
of beautiful workmansliip ; the materials were the hard 
stones of Sweden, which being nearly of equal hardness, 
admitted of being polished after the work was finished. 

An Indian chess-table with an inlaid border, and a num- 
ber of small objects fl'om India, the ground being a white 
marble of a peculiar saccharoidal texture, attracted great 
attention. The pattern was a fine scroll-work, remarkable 
for the extraordinary delicacy and exactness of the stems 
of flowers and the perfect joints — the stems were of flint. 
This and another Indian inlaid-work are said to be of great 
antiquity. No comparison can be instituted between these 
Indian and European works, the mechanical execution of 
the former being at least equal to the best of those which 
have rendered Florence so justly celebrated, while the 
taste and design exhibited in them are greatly superior to 
inlaid work in Tnarhle. 

The great expense of inlaying hard pebbles, which can 
only be cut as gems, and the excellent eflTect that may be 
produced by imitations in which marble of various kinds, 
shells, cement, and glass, replace the jasper and agate of 
Florentine mosaic, have caused the introduction into Eng- 
land, and elsewhere, of a manufacture wliich may be called 
inlaid marble work. In Derbyshire this branch of manu- 
facture has become very important. There are two prin- 
cipal methods of producing marble mosaic ; that folio v\'ed 
in Derbyshire, where a recess is chiselled out of a solid 
block of marble, serving as the ground; and that pursued in 
Devonshire, where the whole surface is in fact veneered; 
numerous marbles of various colors and forms being merely 
cemented together on a base, which may consist of slate, 
or any kind of marble; the Avhole surface being after- 
wards polished together. In Malta the former process is 
followed, while in Russia the malachite inlaid work is per- 



MOSAIC AND PIETEA DURA. 43.3 

formed, as just described. The Duke of Devonshire loaned 
his fine collection of Florentine mosaics to the manufac- 
turers, from which they copied the butterflies, leaves, and 
sprigs of jessamine, for which these mosaics are so cele- 
brated. These works being used as guides, the art of in- 
laying was brought into successful operation, and materials 
foreign to the vicinity, as malachite from Russia, Conti- 
nental marbles, Avanturine and other glasses, from Venice, 
with some cements, have been introduced into them. The 
manufacturers at Matlock, Ashford, Bakewell, Buxton, 
Derby, and Castleton are all doing a thriving business. 

A table with a wreath of flowers of extremely compli- 
cated pattern, and admirably finished, with a vast number 
of detached marbles, of Derbyshire work, ovrned by Mr. 
Vallance, attracted general attention • at the London Exhi- 
bition. Although not to be compared with .the Florentine 
work, there were, nevertheless, much skill and labor be- 
stowed upon it. 

A number of other tables of inlaid work, of the cinque- 
cento style, were likewise well executed. The exhibition 
of Derbyshire inlaid work was very large. 

A mosaic chess-table from the Isle of Man ; from Lisbon, 
interesting specimens of mosaic, composed of sixty sj)eci- 
mens of Portuguese marbles; and from the Cape of Good 

« 

Hope, a peculiar kind of inlaid marble work, were at the 
London Exhibition, and all more or less interesting. 

Clay and Porcelain 3Iosaics. 

The encaustic and mosaic tiles used by the ancients for 
ornamenting houses, for pavements and walls, have of late 
years been extremely well imitated, both in England and 
the United States. 

The encaustic or inlaid tiles are made by pressing clay in 

19 



434 A POPULAR TREATISE ON GEMS. 

the plastic state into an embossed plaster mould, the pattern 
or design on the mould being raised. When the tile is 
withdrawn from the moulS, the outline of the pattern is 
indented, and the indented parts are filled in with colored 
liquid clays, according to the colors it is desirable to pro- 
duce. The surface is then scrajDed quite flat, until the pat- 
^tern appears well defined. The tile is then heated, or as it 
is termed, fired, which brings out the colors to the proper 
tint. 

The Venetian tiles and mosaics are produced by the com- 
pression of powdered clays into metal dies, of any geometri- 
cal form that may be devised, the clays having been previ- 
ously stained with metallic colors. Each tile or tessera is, 
of course, of the same color throughout. When fired, 
they are arranged on a smooth platform, with the faces 
downward, according to the design intended, after which 
liquid Roman or Portland cement is poured upon them, 
and they are thus formed into slabs of any size required. 

The Alhambra or Spanish tiles are made by pressing 
plastic clays into an embossed mould, which forms grooves 
or indentations ; these tiles are then fired, and come out of 
the oven with the pattern formed. The indentations are 
then filled in with enamels of various colors and fired again, 
which produces a brilliant efiect, and renders the tiles suit- 
able either for floors or the interior walls of buildings. 

A mosaic pavement, composed of tesseroe of vitrified clay, 
of several colors and shapes, all produced by machinery 
with great rapidity, and without the necessity of chipping 
any of the tesserae, and at the same time making an endless 
variety of patterns, is produced in England, in the follow- 
ing manner : The clay being prepared in the usual way, 
by washing and sifting, and stained with various metallic 
oxides (oxide cobalt, blue smalts, manganese, zafi're, red 
lead, crocus martis, aurum musivum, oxide chrome, co^3per 



MOSAKf AND PIETRA DUE A. 435 

scales, &c., the principal ingredients used), is formed into 
thin ribbons, about three eighths of an inch thick and from 
tliree to four feet long, by a machine ; out of these ribbons 
the tesserce are cut by a patented machine, with great ra- 
pidity, and when dry are baked in saggers in the usual 
way. 

Pavement slabs are made by laying them J^sserm face 
downwards on a perfectly flat slate, the pattern, of course, 
being reversed, and covering their backs with a layer of 
Portland cement, and two layers of rough thin tiles, care- 
fully embedded in the cement. . In this way strong slabs are 
formed, of from an inch and three quarters to two inches 
thick, which are almost perfectly impervious to moisture or 
rising damp. 

The capitol extension, in the City of Washington* United 
States, is embellished with encaustic tiles ; and both the 
pavement in the halls of the house of representatives and 
senate chamber, and the avenues leading to them, and the 
encased walls, are laid out with bright-colored tiles, in the 
most gorgeous manner. 

Mosaic Tiles made with Sohcble Glass. 

The many useful applications of soluble glass (which 
miay be the silicate of soda, or the silicate of potash, or 
both alkalies combined with the silica), form a new era 
in the production of an artificial stone, which, if properly 
adapted, must ultimately supersede all other artificial 
stones or cements of any kind. If grains of sand, pebbles, 
lime, marble, or even granite, clay, and fluor-spar, are 
mixed with soluble glass into a paste of the consistency of 
putty, and this paste is then moulded into any required 
form, after slowly air-drying and burning the articles thus 
manufactured in a kiln at a bright-red heat, which may be 



436 • A POPULAR TREATISE •X GEMS. 

maintained for any length of time, by which process the 
alkaU contained in the soluble glass is set free, the silica 
combines with the lime, and more particularly with the 
fluor-spar (fluoride of calcium), so durable a cement is 
formed thereb-y, that it will not admit of the smallest 
absorption of moisture, and* consequently is absolutely un- 
attackabie i)y frost. By applying the chloride of calcium 
in ifolution to the cement, the supposed objection that the 
salts of soda, or alkali, are efflorescing by degrees, is hereby 
obviated, for the chloride of calcium at once absorbs the 
alkali. 

Soluble glass may be colored by various metallic oxides, 
so as to produce, when heated, very sharp colors, similar to 
enamels, and may also be employed for a coating over 
other paints, such as fresco, &c. 

As a cement for joinhig together heterogeneous and ho- 
mogeneous substances, it is unsurpassed, and when applied, 
renders the substances so coated both water and fire proof. 

If soluble glass is intended for a varnish, the proper spe- 
cific gravity is 1*165, but for a paint it may be reduced to 
that of water. 

In France, soluble glass is much used in coating com- 
mon building-stones, for the purpose of rendering them 
damp-proof. Marble buildings and damp cellars may be 
made impervious to dampness by varnishing the surface 
with soluble glass ; although the proper mode is to exhaust 
the air from the stone or brick, and then impregnate it 
with soluble glass by pressure. A patent was lately taken 
out in England, for preserving building, pier, and wharf 
stones, by first coating them with a wash of chloride of cal- 
cium, and afterwards by the application of the concentrated 
solution of soluble glass, — repeating the operation several 
times. Soluble glass was introduced into the United 
States, by the author of this work, in the year 1831, under 



MOSAIC AND PIETRA DURA. 437 

the authority of the government, for the purpose of pro- 
tecting the cannon and- balls, exposed to the weather in 
the Brooklyn Navy Yard, against rust ; for this purpose, 
when treated with the various_ coloring pigments, — such as 
oxide of manganese, umber, terra di sienna, ochre, Venetian 
red, ultramarine, &c., — it is admirably adapted. 



-Diamond 
1 



Snpphire- 



Orimtal On ^Ji: Or. 

Topaz Jmethjst Ihibj Ckrysdmil 



ChrYsohtryl ; •Spinell 



Topfiz 



Eiwraid- 



-4'' 



uamarine 



Zircon: 



^^-^(Uiinthy- 



^arnet 



'Cutnamom ■s-tone- 



'Tov rmahne 



-Rod*: Crv<^ial 




'jhmthvst' 



Blood 



-Jasper -'\ , -Agate 



^----Rost qimrtZ' CcU.seve .Prase- AFontiirin stone 

□ ■ □ ■ □ 

-] ---Cliaicedonv ■-, ; Onyjc. 



Sardonyx^ c Ckysoprase " ; Teridote Chr^'soJitc \ 



Opal 










Avfun.oTi, Lapis 
stone Lazuli ^Ta rquoist 



- -Malachite - 



-Amber 



L-^ 



Rost 



Obsidian, Lara Jet LtpidoUte Maiigcai Serpentine Idocrcife Labrador 



-Marble 



-Pdfplivrr 



Ty 



Oranrte- - 



p 



EXPLANATION OF PLATES. 



PLATE II. 



The most remaekable eoijgh Diamonds. 

No. 1. — The Nizam, from India; it weighs 340 carats, is valued 
at five millions of francs, and belongs to the King of Golconda. • 

No. 2. — The great rough Diamond, as describe'd by Tavernier, 
from India, weighing 282| carats. 

No. 3. — The great South Star, from Brazil, weig^ when rough 
254| carats, was found in the mines of Begagem, in the province 
of Minas Geraes, in Brazil. It is as clear as water, slightly tinged 
with yellow ; it is valued at two and a half millions of francs ; it 
is thirty millimetres in height, forty in length, and twenty-seven 
in breadth. Its shape is a twelve-faced rhomboid, presenting 
altogether twenty-four triangles. 



PL. 3 



THE LARGE ROUGH DIAMONDS. 





ROUGH OMMONDS 



PL. 4 









PLATE III. 



Eemaeka-ble eotjgh Diamonds. 

Ko. 4. — The great Spheroidal, six-sided, with forty-eight facets. 
5. — The spheroidal Diamoad, with twenty-four facets. 
6. — A dodecahedral-pentagonal rough Diamond. 
v. — A dodecahedral-rhomboidal rough Diamond. 
8. — An Octahedron, with twenty-four facets. 
9. — An Octahedron, the primary form. 



u 



PLATE lY. 



Kemaekable rough Diamonds. 

N'o. 10. — A rough Brazilian Diamond. 

" 12. — A regular Tetrahedron. 

" 12. — A round, concretional, rough Diamond, called Boort. 

" 18. — A rough Brazilian Diamond. 

" 14. — A rough cubical Diamond. 

" 15. — A rough Brazilian Diamond. 

" 16. — A truncated octahedron Diamond. 

" 17. — A rough Diamond, described by Tavernier. 

" 18. — A triangular crystal of Brazilian Diamond. 

" 19. — An Octahedron, with modified secondary form. 



ROUGH DIAMONDS 



PL, 6. 







/^ 









DIAAfO/VO LATHE. 



PL. 2. 




"fc_3 







THE PRINCIPI£S OF Ci/TT//VO. 

S.o: 



:^ 



a\-e4 





PLATE -y. 



E"o. 1. — The improved Diamond Lathe (exhibited in the Paris 
Exhibition, 1855, by Phillippe). 

No. 2 and 2 a. — The pincers, front and side view. 

The Peinoiple of Cutting. 

No. 3. — a. The table of a brilliant. &. The triangular faces. 
c. The angles terminating into planes, d. Lozenges — i large and 
4 small, e. The planes on the edge of the stone. 

No. 3 a.—f. The angles parallel with the planes, g. Pavilion 
or facets corresponding to Lozenges.* A. The collet of the bril- 
liant. 
No. 4. — A rough Diamond, cleansed. 
" 5.— Out of the crown. 

" 5 a. — The three different cuts, a. The table. &. The girdle. 
c. The collet. 

No. 6. — A Brilliant not recut. 
" v. — A Brilliant recut. 
" 8. — Kose Diamond, a. The crown. &. The facets. 

* Lozenge is the geometrical form of a rhomb. 



PLATE Yl 



The most oelebeated out Diamonds. 

No. 1. — The Grand Mogul; it weighs 279 carats, and is valued 
at twelve millions of francs. 

No. 2. — The Orlow, the great Eussian Diamond, weighs 195 
carats, and is the size of a pigeon's egg : cost two millions of francs 
and a pension of one hundred thousand francs.* 

No. 3. — The table Diamond of Ta vernier, weighing 242^ carats. 
" 4c. — The Poiar Star, weighing 40 carats. 
" 5. — The Shah, belonging to the Russian crown, weighing 
95 carats. 



* It is on the top of the Bassian sceptre, and has the form of a knob of a cane ; the 
under sarface is a plane. 



THE MOST CELEBRATED CUT DIAMONDS. 



PL.G. 







PL.7. 



THE. MOST CELEBRATCD CUT DIAMONDS 

6 7 







/«? 





//» 





/2.flt 




PLATE YII 



The oelebeated out Diamonds. 

No. 6. — The Nassack, weighs 78| carats; was sold, in 1839, foi 
seven thousand six hundred pounds sterling, to the Marquis oi 
Westminster. 

No. 7. — The great India half-cut Diamond, weighing 112| 
carats. 

•No. 8. — A brillianted Eose in pear-shape, from Itdia, weighing 
16 carats. " , 

No. 9. — Another Rose in pear-shape, weighing 94| carats. 

No. 10. — A recut India Brilliant, weighing 29 carats. 

No. 11 and 11 a. — The South Star of Halphen, weighing 124 
carats. 

No. 12 and 12 a. — The Regent, or Pitt; it weighs 136 carats, 
belongs to the French crown, is valued at five millions of francs, 
and is certainly the best-proportioned Diamond in the world ; it 
is perfectly pure and transparent, and sparkles with a magnificent 
play of color. 



PLATE YIII. 



The celebrated out Diamonds. 

No. 13. — The Piggot, belonging to England, weighs 82 carats. 

Ko. 14:. — The Pacha of Egypt's Diamond, weighs 49 carats. 

No. 15. — The Koh-i-noor, as it came from India ; and 15 a, its 
present form, "from a side view. • 

No. 16. — An India pear-shaped BriUiant, weighing 31^ carats. 

No. 17. — A Half-Brilliant, faceted, weighing 14] carats. 

No. 18. — Large Rose Diamond, of 280 carats. 

No. 19.— ^An irregular Eose Diamond, in pear form, weighing 
20 carats. 

No. 20. — An India Brilliant, described by Ta vernier, weighing 
52 carats. 

No. 21 and 21 a. — ^Large table Diamonds, step-cut. 



THE MOST CELEBFi/ITED OUT DIAMO/VDS , PL. 8. 



73 




rs cu 




THE MOST CELEBRATED CUTDIAMONDS , 



PL. 9. 




PLATE IX. 



The oelebeated out Diamonds. 

No. 22. — The great Austrian Brilliant, belonging to the Grand 
Duke of Tuscany, weighing 139^ carats; valued at seven millions 
of dollars. 

No. 23. — The Eugenie Diamond, belonging to the Empress oi 
France, weighing 51 carats. 

No. 24. — The Hope Diamond, a beautiful blue Diamond, weigh- 
ing 44i carats. 

No. 25.— A Brillolet of 16f carats. 

No. 26. — A knob-shape of 10 carats. 

No. 27. — A table-shape of 10 carats. 

No. 28,^ — A flat Diamond of 20 carats. 

No. 29. — A flat Diamond of 14 ^carats. 

No. 30 and 30 a.^ — The celebrated Sancy, belonging to the 
French crown-jewels, weighing 33|- carats, of pear-shape ; is 
valued at one million francs. 

No. 31. — A large cleaved Diamond, of 64 karats, from India. 



PLATE X. 



J!^o. 1. — Rock-Cry stal Group, from Arkansas, U. S. 
Size and weight of Diamonds, both round and square, from that 
of half a carat to 184 carats. 




PL.X. 




PL.XL 



PLATE XI. 



Ameeioan Fancy Maebles. 

No. 1. — California Marble. m • 

" 2. — Yerde Antique, from Yermont. 

" 3. — Shell Marble, from New York. 

" 4. — Tennessee Marble. 

" 5. — Hale's Breccia Marble, from Lancaster, Pa. 

" 6. — Potomac Marble. 

" 1. — Yariegated Marble, from the State of New York. 



PLATE XII. 



No. 1. — ^Black Marble, with petrified volutes {Pyramidella tur- 
tinella). ^ • 

J^o. 2. — Ke^, green, and white brecciated Marble, from Sicily. 

No. 3. — Red mottled Marble, tertiary fresh-water Limestone, 
from Swabianl^l^, cut parallel to the planes of the layers. 

No. 4. — Pale, yellow, and violet Marble, from the Jura, in 
"Wiirtemberg. 

No, 6. — Reddish-yellow and bluish-red mottled Marble, from 
Wiirtemberg. 

No. 6. — Marble, tertiary, cut perpendicularly to the planes ot 
the layers, from the Alps. 

No. 7. — ^Pale-yellow Marble, and violet Flakes, from Wiirtem- 
berg. 



PLXU. 




PLATE XIII. 



No. 1. — Tertiary brecciated Marble, from the Pyrenees. 

ISTo. 2.' — Red Granite, consisting of red felspar, grey quartz, anc" 
black mica, from Upper Egypt ; used by the ancient Egyptians in 
their monuments. 

No. 3.— Fibrous Calcite, or so-called Thermal Tufa, Sprudel- 
stein, from Carlsbad. 

No. 4. — Compact Brown-spar, from Gibralter. 

No. 5. — Agate Marble, from Algiers. 



PLATE XIV. 



// 

/Ko. 1. — Kyanite, light-blue and oblique rhombic prism, with 
/ 'truncation, from St. Gothard. 

'Ro. 2. — Amphibole or dark-green Hornblende, Actinolite, an 
oblique rhombic prism, from Tyrol. 

No. 3. — Precious Serpentine, in right rectangular prisms, from 
Norway. 

No. 4. — Lumachelli or Fire Marble, containing fossil shells; the 
variegated colors are owing to nautilus or ammonite, from 
Corinthia. 

No. 5. — Ruin Marble, cut perpendicularly to the ••planes of the 
layers, from Tuscany. 

No. 6. — Pea-stone, calcareous Stalactite, from the hot springs 
of Carlsbad. 

No. 7. — Dark-brown ribbon Agaie, Arabian Onyx, from the 
East Indies. 

No. 8. — Pale-yellow Marble, from Florence. 

No. 9. — yariegated Marble, containing Corals, from the transi- 
tion rocks of Nassau. • 

No. 10. — Red brecciated Marble, from Italy. 

No. 11. — Black Porphyry, from Sweden. 




PL. XIV. 




PL. XV. 



PLATE XY. 



Ko. 1. — Egyptian Jasper. 

No. 2. — Eibbon Jasper, striated with red and green, from 
Siberia. 

l!To. 3, — Pudding-stone or Quartz Conglomerate, from Scotland. 

Ko. 4. — Horny-colored Agate, from the East Indies. 

No. 5. — Chrysolite, from the East Indies. 

No. 6. — Noble Garnet, Pyrope, from Bohemia. 

No. 7. — Dark-yellow Topaz, burnt, and called Balais, from 
Brazil. 

No. 8. — Granite, from Milan. 

Xo. 9. — Wood Opal, a petrified pine, from Hungary. 

No. 10. — Black ribbon Agate, from the East Indies. 

No. 11. — Green Tourmaline (Brazilian Emerald) in Dolomite, 
from St. Gothard. 

No. 12. — Moss Agate or Mocca-stone, from the East Indies. 

No. 13. — Dark Topaz, from Brazil. 



PLATE XYI. 



No. 1. — Black and white mottled Marble, from the monntaic 
limestone of Ardennes. 

No. 2. — Red antique Porphyry, from Upper. Egypt. 

No. 8. — Blue Copper, Azurite, from Germany. 

No. 4, — Malachite, Green Copper, from Siberia. 

No. 5.— Natrolite on Clinkstone, from Bavaria. 

No. 6. — Clear-yellow Amber, inclosing several flies, from the 
coast of the Baltic, near Dantzic. 




PLXV/. 



PLJ(V//. 




PLATE XYII. • 



No. 1. — Dark-green Serpentine, from the Apennines. 

No. 2. — Amazon-stone or apple-green Felspar, an oblique rhom- 
bic prism, from the Ural Mountains. 

No. 8. — Fortification Agate, from Oberstein. 

No. 4. — Green Porphyry Felspar, from Greece. 

No. 5. — Serpentine, Ophicalite, or Verde de Corsica duro, from 
Corsica. 

No. 6, — Labrador Felspar, from Labrador. 



INDEX. 



A. 

A jour, what, 169. 

Acicular crystals, 71. 

Adamant, the diamond, 188. 

Adalaria, a felspar, its hardness, 78; re- 
fraction, 87 ; described, 812. Varieties, 
viz: moonstone, sunstone, girasol, fish- 
eye, Ceylon or water opal, 813. 

Agaric mineral, 865. 

Agatized wood (hornstone), 277. 

Agate, described, 283 ; a mixture of quartz, 
ib.; varieties, ib,; agate works at Obers 
tein, 286; coloring of, 287 ; Iceland agate 
or obsidian, 309. 

Alabandic carbuncles, 251. 

Alabaster, Italian (sulpliate of lime), 842; 
oriental (carbonate of lime), ib. 

Albite, 69, 70. 

Allochroite, a garnet, 249. 

Almandine, fusibility, 115 ; almandine ru- 
by, a spinellfij 228; almandine garnet, 
248. 

Almas, oriental name for diamond, 188. 

Alum, 23; refraction of, 88. 

Alumina, test of, 122. 

Amazon stone (felspar), 315. 

Amber, degree of hardness, 80; a resin, 
843; described, ib.; locality, 845; tech- 
nical names of varieties, 346 ; insects in, 
849. 

American diamonds, 210; marbles, 371, 
383. 

Amethyst, degree of hardness, 80; orien- 
tal, a sapphire, 215; described, 267; ori- 
gin of name, 266. 

Amianthus, lustre of, 95. 

Ammonia, test of, 121. 

Amorphous crystals, 19. 

Amulets, 149, 

Analcime, 27. 

Anatase, 88. 

Andalusite, 74 

Anhydrite, 74; its refraction, 87. 

Anorthotype system, 21. 

Anthraconite (stink-stone, swine-stone), 
860. 



Antimony, glance, fusibility of, 116; test 

of, 123. 
Apatite, 70 ; hardness, 78 ; described, 887. 
Aplome, garnet, 248, 250. 
Apophyllite, refraction of, 88. 
Apyrite, tourmaline, 255. 
Aquamarine, sapphire, 216; topaz, 280; 

beryl, 240. 
Argentine (calcareous spar), 866. 
Armenian stone (lapis lazuli), 828. 
Arragonite, 74; double refraction ot, 87; 

electricity, 99. 
Arsenic, test of, 128; arseniates of lead 

and copper, 88. 
Asparagus stone, 887. 
Asteria, star sapphire, 216, 217. 
Augite, 51, 56, 68, 75. 
Automolite, 63. 
Avanturine quartz, 272. 
Axinite (thumerstone), 54 ; de8crib«d, 811. 
Azure stone (lazulite), 824. 



B. 

Bacillary, 71. 

Balais ruby, variety of spinelle, 227. 

Baryta, test of, 121. 

Barytes, 48. 

Bastard diamond, 168. 

Beeralston quartz, 70. 

Beryl, 56 ; a real gem, 186 ; described, 240. 
Varieties—aquamarine, Siberian aqna- 
n^arine, aquamarine chrysolite, ib.; lo- 
cality, ib.; cutting, ib.; remarkable spe- 
cimens, ib. 

Binary compounds with oxygen, table o^ 
107. 

Bisel, what f 161. 

Bismuth, blende, 23; test of, 124 

Black diamonds, 207, 210. 

Bloodstone (heliotrope), 2S2. 

Blowpipe, use o^ 113. 

Blue copper, 58. 

Blue diamond, celebrated, 206. 

Boracic acid, 120. 

Boracite, 28, 28 ; refraction oi; 8T. 



458 



INDEX. 



Borax, doable refraction of, 88; reagent, 

116. 
Botryoidal, 72. 
Brachyiliagonal, 46. 
Brachydornes. 47. 
Brachypyramids, 47. 
Brazil, discovery of diamonds in, 187; 

revenue from diamonds in, 201. 
Brewsterline, 265. 
Brilliant, the, 161. 
Brillionets, 161. 
Bromine, 119. 
Bronzite, fusibility of, 116. 
Brown spar, 56. 
Burning of gems, 171. 

0. 

Gabocbon cut, 165. 

Cachelong, an opal, 307. 

Cadmium, test of, 125. 

Cairngourm crystals, 261. 

Calamine, 55. 

Calc spar, 43. 65, 66, 70, 73 ; hardness, 78 ; 
double refraction, 86 ; varieties of, 364. 

Calcareous scheelite, refraction of, 88. 

Cameos, shell, 425. 

Cannel coal, described, 354. 

Carat, origin of the word, 181 ; weight of 
four grains, ib. 

Carbon, 120. 

Carbonate of soda, reagent, 116; refraction 
of carbonates, 87 ; electricity, 99. 

Carbuncle (see Spinelle), 228 ; garnet, 251. 

Carengeair's goniometer, 5S. 

Cornelian, hardness o^ SO; described, 279. 

Cat's-eye quartz, described, 270. 

Caves, list of American, 380. 

Cerium, test of, 127. 

Chabasite, 56, 65. 

Chalcedony, 73; hardness of, 80; refrac- 
tion of, 88; described, 277. Varieties— 1, 
Chalcedonyx ; 2, Mochastones ; 3, Rain- 
bow: 4, Cloudy; 5, Plasma; 6, Semicar- 
nelian or ceregat ; 7, Sappharine ; 8, St. 
Stephen's stones, 278; varieties of, 77. 

Chalcopyrite, 64. 

Chalk, 365. 

Chemical properties of minerals, 102 ; reac- 
tion, 113. 

Chlorine, 119. 

Chlorophane (a fluor spar), 835. 

Chromate of lead, refraction o^ 87. 

Chromium, test of, 127. 

Chrysoberyl, degree of hardness, 80 ; real 
gem, 186; same as cymophane, 225. 



Chrysolite (Peridote, olivin), hardness of, 
80; real gem, 136; oriental, a sapphire, 
216; refraction of, 87; Ceylon, atourma-r 
line, 256 ; described. 294. 

Chrysoprase, described, 292 ; value, 294. 

Cinnabar, refraction of, SB. 

Cinnamon stone or Essonite, 253 ; see Hya- 
cinth de Ceylon. 

Cleaning gems. 172. 

Cleavage, varieties o^ 76. 

Clinopinacoids, 51. 

Clinoprisms, 51. 

Clinopyramids, 51. 

Coal, 354; American coal-fields, ib. 

Cobalt, solution o^ reagent, 117; test of, 
125. 

Cobaltine, 30, 31. 

Collet the, explained, 161. 

Colophon ite, a garnet, 249. 

Color, change of, 93; table of colors of 
minerals, 96; of gems; 186. 

Combinations, 31. 

Conazeranite (felspar), 314. 

Copper, test of, 126. 

Coral, described, 419; varietiesof red, 422. 

Cordierite, a real gem, 1 36. - 

Corundum, hardness, 78 ; refraction of, 87 ; 
description of, 214; see Sapphire. 

Corundum, common, or Diamond spar, de- 
scribed, 223 ; granular, or emery, 224. 

Crown-jewels of France, value of, 207. 

Crown-jewels of Queen Victoria, 210. 

Cryptoline, 265. 

Cryptocryslalline minerals, 73. 

Crystalline, 19. 

Crystallized, 19. 

Crystals, defined, 20 ; described, ib. ; sys- 
tems of, ib. ; imperfections of, 54 ; striae 
55 ; drusy, 56 ; measurement, 58 ; macles 
or twin crystals, 61 ; irregular aggrega- 
tion, 70. 

Cyanite, 73 ; described, 327. 

Cymophane (oriental chrysolites), refrac- 
tion of, S7 ; see Chrysoberyl. 

D. 

Deltoid dodecahedrons, 28; sign, 80. 

Derivation of forms, 27. 

Diamond, 24, 25, 29 ; hardness of, 78, 80 5 
double refraction of, 87 ; first cut by Ca- 
radossa, 151 ; manner of cutting, 156, 188; 
polishing, 158; forms of, 161 ; discovery 
in a diamond lens, 182 ; general account 
of; 183, etc. ; pure carbon, 184 ; artificial, 
ib. ; form^f crystals, 185 ; color, ib. ; the 



INDEX. 



459 



compact, ib. ; the original bed of, 18T ; 
loss in cuttini:, 193 ; Hindoo division of, 
195; value, ib. ; color, purity, ib.; de- 
gree of clearness, ib. ; cut and size, 196 ; 
prices of, 197-8; celebrated diamonds, 
154. 193, 203; the largest known, 208 ; in 
Victoria's crown, 211 ; at the Industrial 
Exhibition, 212. 

Diamond grinders, 155. 

Dimorpl)ism, 110. 

Dioptase, double refraction of, 88. 

Disthene (Kyanite, sappare), described, 
327. 

Ditetragonal, pyramids, S6. 

Divelsteene, 156. 

Dodecahedrons, subdivided, 22. 

Dolomite,, double refraction of, 87. 

Double facet cut, 165. 

Doublets, 180. 

Druses, 71. 

Drusy crystals, 56. 

Dyakisdodecahedron, 80 ; sign, 81. 



E. 

Edingtonate, double refraction of, 88. 

Electricity of minei-als, 99. 

Electro-chemical elements, table of, 105. 

Electroscopes, 99. 

Elongated brilliant facet cut, 165. 

Emerald, hardness of, 80; double refrac- 
tion, 8S ; a real gem, 136 ; the oriental, a 
sapphire, 216; described, 235; emerald 
proper, ib.; how cut, 237; value, ib.; 
remarkable emeralds, 238 ; the Duke of 
Devonshire's, 239 ; the Brazilian, a tour- 
maline, 256. 

Emery, a common corundum, 224 

Engraving on gems, 167. 

Essonite, or cinnamon-stone; hardness of, 
80; real gem, 136, 250; described, 253. 

Euclase, double refraction of, 87; descrip- 
tion of, 234. 



Facets, 161. 

Fahlore, 63. 

Felspar, 52, 53, 75; described, 312; com- 
mon, 315; adularia, 312; murchisonite, 
814; leclite or hellefliata, conazeranite, 
ib.; amazon-stone, 315; porphyry, 391; 
sienete, 393. 

Fi»b-eye (adularia), 813. 



Fluor spar, crystalline forms, 28, 24, 25, 56, 
63, 65, 70 ; hardness, 78, 80 ; double re- 
fraction of, 88 ; electricity, 99 ; describ- 
ed, 333. 

Fluorine, test for, 120. 

Foil, use of, 169. 

Form, primary, 26; semi-tesseral, 28 ; par- 
allel semi-tesseral, 30. 

Forms of crystalline aggregates, 71. 

Fortification agate, 284. 

Fracture surfaces, 73. 

Fusibility, test minerals as to, 115. 



G. 

Galena, 23, 24, 56, 63. 

Garlic, used in repairing gems, 170. 

Garnet, 23, 25, 27 ; hardness of, 80 ; double 
refraction ot; 88; magnetic, 100; a real 
gem, 136 ; described, 247 ; varieties, 248 ; 
Syrian, Bohemian, Ceylonian, Aplome, 
ib.; precious or almandine, 248 ; colopli- 
onite, 249 ; allochroite, ib.; grossular, 
250; topazollte, ib.; melanite, pyrena- 
ite, ouwarowite, ib.; the ancient car- 
buncle, 251. 

Gems, 135 ; enumerated, 136 ; color, grav- 
ity, and hardness of, ife.; chemical char- 
acter, 139 ; composition, ib.; artificial 
production, 140; geological character, 
145; geographical distribution, 146; di- 
vision and nomenclature, 147; history 
of, 148 ; superstitions as to, 149 ; sculp- 
ture in, 151; grinding, 153; engraving, 
167; sawing and drilling, 168; polishing 
materials, ib.; heightening color of, 169 ; 
setting, 171; cleaning of, 172; imita- 
tions, i&.; 1, pastes, ^?>.; 2, doublets, 180 ; 
3, burning, 180 ; price of, 181 ; optical 
use of, 181. 

Girasol sapphire, 216 ; fire opal, 304 ; adu- 
laria, 313. 

Girdle, in diamonds, what ? 161. 

Glucina, test of, 123. 

Goldstone, a paste, 273. 

Goniometers, 58. 

Goutte de sang, a spinel le, 228. 

Grand mogul diamond, 193, 203. 

Granite, described, 896 ; American varie- 
ties, 397. 

Gray copper ore, 28, 63. 

Grossular garnet, 250. 

Gypsum crystals, 51, 56, 68, 74; double 
refraction of, 88 ; satin gypsum, 841 ; al- 
abaster, ib. 



460 



INDEX. 



H. 

Haematite, 65. 

Hardness of minerals, 78 ; Moh's, scale of, 
ib.; rough scale, 79 ; of precious stones, 
80; of gems, 136. 

Hatchet-stone (jade), 361. 

Hausmanite, 64. 

Hanyne, described, 322. 

Heliotrope, described, 282. 

Hellffliata, or Leclite (felspar), 314. 

Helvine, 28. 

Hemihedric crystal, 21. 

Hemimorphism, 54 

Hemiorthotype system, 21. 

Hexagonal system, 21, 39; pyramids 40; 
dihexagonai, 41 ; rhombohedral, 42. 

Hexahedron, 22, 23 ; sign of, 27. 

Hexakisoctahedrons, 25 ; sign of, 27. 

Hexaldstetrahedron, 28; sign, 30. 

Holland diamond, 206. 

Holohedric crystals, 21, 22. 

Hope diamond. 206. 

Hornblende, 68, 320. 

Hornstone, described, 277. 

Hyacinth, hardness of, 80; oriental, a sap- 
phire, 215; a variety of zircon, 246; de- 
scribed, 247. 

Hyacinth de Ceylon (Essonite, or cinna- 
mon-stone), 253. 

Hyaline, 19. 

Hydrate of .magnesia, double refraction 
of, 88. 

Hydrometer, 81. 

Hydrophane, a variety of opal, 305 ; curi- 
ous property, ib. 

Hydroxide of iron, double refraction of, SS. 

Hypersihene, not hornblende, 320; de- 
scribed, ib. 



I. 



Iceland spar, 66 ; double refraction of, 86 ; 
described, 364 

Icositetrahedrons, 22, 24; sign of, 27. 

Idocrase, double refraction of, 88; describ- 
ed, 321. 

Ignoble metals, 101. 

Itnitaiions of gems, 172.' 

Indicolite (Brazilian sapphire), 256. 

Iodine, test for, 119. 

lolice. real gem, 136; described, 297; di- 
ohroite, peliom, lynx and water sapphire, 
298. 

Iridescence, 98. 



Iron, double refraction of, 88; test ot^ 

127. 
Iron pyrites, 30, 31, 55, 63. 
Irregular aggregation, 70. 
Isomorphic sulJfetances, 111. 
Isomorphism, 110. 
Itacolumite, diamond-bearing rock, 183. 

J. 

Jade (nephrite, hatchet-stone, punamu), 
described, 361. 

Jargon (see Zircon), 244 ; described, 246. 

Jaspachates, a variety of agate, 284 

Jasper described, 273 ; varieties : 1, Egyp- 
tian ; 2, Eibbon spar, 276 ; jasper opal, 
308. 

Jet, hardness of, 80 ; described, 353 ; a bi- 
tuminous coal, ib. 

Jewish tribes, gems allotted to, 149. 

Jeweller's wax, 172. 



K. 

Kaolin, 75. 

Kneeshaped crystal, 64. 

Kohinoor, a celebrated diamond, 154; its' 

loss in cutting, 193; history of, 208. 
Kuinur, a celebrated diamond, 154. 
Kyanite (sappare, disthene) described, 827. 



Labradorite, 70 ; not felspar, 317. 

Lamellar, 71. 

Lapidaries, ancient, 151; society of, 153; 

gem lapidary, 163 ; common, 164 ; his 

apparatus, ib. 
Lapis lazuli, or Armenian stone, described, 

322 ; uses of, 323. 
Lava described, 360. 
Lava, black glass lava, or obsidian, 810. 
Lazulite, hardness of, 80 ; azure-stone, 324 ; 

used to imitate lapis lazuli, ib. 
Lead, 66 ; test of, 125. 
Leclite (felspar), 314. 
Lepidolite, described, 389. 
Leucite, 27. 
Lievrite, 48. 
Lithia, test of, 121. 
Lime, tesi of, 122. 
Litiiographii! stone, 366. 
Love's arrows, a rock crystal, 261. 
Lustre, 93 ; degrees of, 94 ; varieties of, ib 
Lyncurium, not tourmaline, 258. 



INDEX. 



461 



M. 

Macles or twin crystals, 61. 

Macrodiagonal, 46. 

Macrodomes, 4S. 

Macropinacoid, 48. 

Macroprisms, 48. 

Magnetic iron ore, 24, 63. 

Malachite, 74; hardness of, 80; describ- 
ed, 385; beautiful articles made of, 
338. 

Manganese, test of, 125. 

Marble (Carbonate of lime), described, 264 ; 
best localities, 366 ; ancient marbles, 367 ; 
French, ib. ; English, 368 ; varieties of 
Derbyshire, ib. ; marble statuary, 370, 
376 ; American marbles, 371, 383 ; white, 

. ib. ; encrinital or bird's-eye, 372 ; mar- 
bles, &c., in N. Y. Geological cabinet, 
373 ; breccia, 375 ; serpentine or verd an- 
tiquej ib. ; leocadia breccia, 376; Egyp- 
tian, 3S2 ; Italian, ib. ; shell marble, 
385. 

Marcasite, 66 ; or pyrites, 390. 

Marekanite, brown obsidian, 310. 

Measurement of crystals,' 58. 

Meerschaum, described, 357; uses of, 
858. 

Meionite, double refraction of, 38S. 

Melanite, garnet, 250. 

Mellite, double refraction of, 88. 

Mercury, test of, 124. 

Mica, double refraction of, 88 ; described, 
389. 

Microcosmic salt, reagent, 116. 

Mineralogy, how limited in this work, 
16. »■ 

Minerals, forms of. 19 ; crystalline, amor- 
phous, ib. ; physical properties, 75; hard- 
ness and tenacity, 78 ; specific gravity of, 
80; optical properties, 84; double re- 
fraction, 85 ; polarization of light, 89 ; 
pleochroism, 92 ; iridescence, 93 ; lustre, 
ib. ; color, 95; phosphorescence, 98; 
magnetism, 100 ; smell, taste, touch, 101 ; 
chemical properties, 102; composition, 
ib. ; influence of chemical composition 
on external character, 109; chemical re- 
action, 113; fusibility, 114; solubility, 
117 ; classification, 129 ; orders of, 134. 

Mispickel, 66. 

Mix facet cut, 164. 

Mocha Stones, chalcedony, 278. 

Mohs ; his system of crystallization, 21 ; 
scale of hardness, 78. 

Molybdite, double refraction of, 88. 



Monoclinochedric system, 21, 49 ; its forms, 

49; combinations, 51. 
Months, gems, allotted to, 149. 
Moonstone (Adularia), 313. 
Moroxite, an oolite, 387. 
Mosaic, 426; Koman, 427; Florentine or 

pietra dura, 429; clay and porcelain, 

433. 
Murchisonite (felspar), 314. 

N. 

Nassak diamond, 193; its value, 200, 204, 

210. 
Natrolite, fusibility of, 115; described, 832. 
Naumann, his system of crystallization, 21. 
Nepheline, double refraction of, 88. 
Nephrite or jade, 361. 
Nicholson's hydrometer, 81. 
Nickel, magnetism of, 100; test of, 125. 
Nitric acid, test, 119. 
Nizam diamond, 208. 
Noble metals, 103. 
Non-metallic elements, ll3. 

o. 

Obsidian, hardness of, 80 ; described, 309. 

Octahedron, 23; primary form, 26; how 
distinguished, ib. 

Oligoclase, 69. 

Olivin, or Chrysolite, 294. 

Ouwarowite, garnet, 250. 

Onyx, carnelian, 280 ; agate, 288 ; describ- 
ed, ib. ; cameos of, ib. 

Oolite, a calcareous spar, 365, 386. 

Oolitic crystals, 73. 

Opal, 73; hardness, 80; double refraction, 
88 ; iridescence, 93 ; described, 299 ; pre- 
cious opal, ib. ; mother of opal, 301 ; cel- 
ebrated specimens, 302; fire opal, or 
girasol, 804; common opal, 305; hydro- 
phanes, ib. ; semi-opal, 306; -wood opal, 
ib. ; cachelong, 307; Jasper opal, 308; 
Ceylon or water opal, ib. 

Orders of minerals, 137. 

Oriental and occidental gems, 147. 

Orlow diamonds, 203. 

Orthopyramids, 51. 

Orthoprisms, 51. 

Orthopinacoids, 51. 

Orthotype system, 21. 

Orthoclase, 52, 68; fusibility, 115. 

Oxaliverite, double refraction of, 88. 

Oxide of tin, double refraction of, 88. 

Oxidized stones, 134 

Oxidized ores, 134. 



462 



INDEX. 



P. 

Pastes and artificial gems, 172 ; receipts for 
colored. 176 ; how detected, 179. 

Paunched diamonds, 195. 

Pavilion facets, 162, 164 

Pearls described, 400 ; how formed, ib. ; 
localities, 401 ; value of, 407 ; United 
States pearls, 409 ; artificial, 415. 

Peliom, a variety of iolite, 298. 

Pentagonal dodecahedron, 30; sign, ib. 

Pentagonal dodecahedron, and pentagonal 
icositetrahedron, not observed in nature, 
31. 

Peridote (see Sapphire, Chrysolite),216, 294. 

Phosphates of lead and lime, double re- 
fraction of; 88. 

Phosphate of lime, 888; Its uses, ib. 

Phosphorescence, 98. 

Phosphoric acid, test of, 118. 

Phosphorite, 388. 

Pietra dura (Florentine mosaic), 429. 

Piggot diamond, 206. 

Pisolite (calcareous spar), 865, 886. 

Plasma, chalcedony, 218. 

Plaster of Paris; a gypsum, 842; constitu- 
ents, ib. 

Platinum, test of, 126. 

Pleochroism, 92. 

Point diamonds, 161. 

Polar-star diamond, 206. 

Polarization of light, 89; instrument for 
observing, 90. 

Porodine, 19. 

Porphyry, a compact felspar, 891 ; Ameri- 
can varieties, 892. 

Potassa, test of, 121. 

Prase, common quartz, described, 271. 

Prehnite, 56. 

Prismatic topaz, hardness, 78. 

Pseudomorphism, 74. 

Punamu (jade), 361. 

Pyramidal system, 21. 

Pyrenaite, garnet, 250. 

Pyrites described, 890 ; also called Marca- 
site, ib. 

Pyrope, a garnet, 248. 

Q. 

Quartz— common, Rose quartz, cats-eye, 
prase, avanturine, 269. 

Quartz crystals, 55, 56; hardness, 78 ; double 
refraction of, 87, 88 ; an oxidized stone, 
134 ; a gem, 186 ; described, 259. 

Que«D Yictoria^s orown, 210. 



R. 

Rainbow chalcedony, 278. 

Red silver, double refraction. 88, 

Refraction, double," 85; table of, 87, 

Regent diamond, 154, 193, 204 

Reniform crystals, 72. 

Rhombic system, 21, 45. 

Rhombic dodecahedron, 23 ; sign of, 27, 

Rhombohedral system, 21, 

Rhombohedron, 42 ; combinations, 44, 

Ribbon spar, 276. 

Rock of Gibraltar, carbonate of lime, 386i 

Rock crystal, 78; hardness of, 80; de- 
scribed, 260 ; varieties, 261 ; specimens, 
262; water in them, 265. 

Rock salt, hardness, 78) double refrac- 
tion, 88. 

Rose diamond, 162. 

Rose manganese, described, 391. 

Rose quartz, 269. 

Rubellite, double refraction, 88 ; a real 
gem, 136 ; tourmaline, 255. 

Ruby, hardness of, 80 ; a variety of sap- 
phire, 214, 215. 

Ruby cat's-eye, 216. 

Ruby spinelle, almandine, balais, varie- 
ties of spinelle, 227, 228. 

Russia, discovery of diamonds in, 189. 

Rutil, double refraction of, 88; 

s. 

Saline ores, 134. 

Saline stones, 134. 

Sancy diamond, 204 ; history of, ib. 

Sappare (kyanite, dfethene), described, 827. 

Sappharine, a chalcedony, 278. 

Sapphire, hardness of, 80 ; iridescence of, 
93 ; real gem, 136 ; synonymous with 
corundum, 214 ; description of, ib.; va- 
rieties, 215; ruby, oriental hyacinth, 
amethyst, sapphire, and topaz, 215; 
aquamarine, chrysolite, and emerald, 
216; its constituents, 216; locality, 217; 
mode of cutting, i&./ uses, 219; value, 
ib, ; remarkable sapphires, 221, 222 ; 
Brazilian sapphire or indicolite, a tour- 
maline, 256 ; lynx and water sapphire, 
iolites, 298. 

Sarda, ancient name for Carnelian, 279. 

Sardonyx, a carnelian, 280; agate, 289; 
cameos and intaglios, 290. 

Satin gypsum, described, 341. 

Satin spar, described, 840. 

Scal«nohedroD, 4S. 



I N » E X 



403 



Scapolite, 79. 

Schlaggenwald fluor spar, 70. 

Schorl, electric, a tourmaline, 256; origin 
of the name, 258. 

Sculptors in gems, 152, 

Selenium, test for, 118. 

Semi-carnelian. 278; a phalcedony, t6. 

Semi-tesseral forms, 28. 

Serpentine, described, 362. 

Setting ofgems, 171. ■ 

Shah diamond, 206. 

Shrugging in diamonds, 195. 

Siberite, a tourmaline, 255. 

Siderite, 56. 

Sienite (felspar and hornblende), 893 ; 
American varieties, 394. 

Signs, crystallographic, 27. 

Silver, test of, 126. 

Soda, test of, 121. 

Solubility, 117. 

Soluble glass, 435. 

Somervillite, double refraction of, 88. 

South star diamond, 193, 210. 

Specific gravity of minerals, 80 ; how as- 
certained, ib.; of gems, 136. 

Spinel, spinelle, 23, 63; hardness, 80; 
double refraction, 87; real gem, 186; 
described, 227; constituents, ib.; varie- 
ties, 227, 228; ruby spinelle, ruby balais, 
almandine ruby; goutte de s&ns,ib.; im- 
, itation, 229. 

Stalactite, 73, 365; described, 380. 

Stalagmite, 73 ; described, 380. 

Star facets, 162. 

Star of the south, 210. 

Staurolite, 66. 

Ste\)hanite, 66. 

Stilbite, 48, 56. 

Strahlstein, fusibility of, 115. 

Striae, 55. 

Strontia, test of, 122. 

St. Stephen's stone (chalcedony), 278. 

Stygmite, a carnelian, 281. 

Sulphate of baryta, 87. 

Sulphur, 48; refraction of, 87 ; test for, 118. 

Bunstone, sapphire, 216; iridescence of, 
93 ; adularia, 313. 

Systems of crystals, 21. 



T. 



Table of a diamond, 161. 
Table diamond, 163. 
Talc, hardness of, 78. 
Tantalium, test of, 128. 



Tchingtching (lapis lazuli), 325. 

Tellurium, test of, 124. 

Tenacity of minerals, 80. 

Terminology, 19. 

Tesseral, or tessular system, 21 ; described, 
22. 

Tetragonal system, 21, 34; closed forms, 
35; tetragonal pyramids, ?&.; ditetrago- 
nal, ib.; tetragonal sphenoids, 36; tet- 
ragonal scalenohedrons, ib.; open forms, 
36; tetragonal prisms, ib. 

Tetragonal crystals, how distinguished, 37. 

Tetrahedral form, 28 ; its sign, 29. '"'^ 

Tetrakifahexahedrons, 24; sign ofr ^T^rf "-^ 

Thorina, test of, 123. 

Thumerstone, or axinite, 311. 

Tin, test of, 125 ; tin ore, 64. 

Titanium, test of. 129. 

Topaz, crystal, 48 ; hardness, 80 ; optical 
power, 87 ; electric, 99 ; a real gem, 
136; description of, 229 ; varieties, 230 ; 
cutting of, 231; localities, 232; imita- 
tions, 233; engraved topazes, ib.; topaz 
of the ancients, 229, 234. 

Topazolite, 250. 

Tourmaline, 55, 56 ; double refraction ofi 
88 ; polarization of light, 89 ; real gem, 
136; described, 254; composition of, 
255; 1. Siberian (siberite, rubellite, apy- 
rite), ib.; 2. Indicolite (Brazilian sap- 
phire) ; 3. Brazilian (emerald) ; 4. Ceylon 
(chrysolite) ; 5. Electric schorl, 256 ; lo- 
calities, ib.; fine specimens, ib.; not lyn- 
curium of the ancients, 258. 

Triakisoctahedron, sign of, 27. 

Triclinohedric system, 21, 52 ; pyramids, 
53 ; combinations, ib. 

Trigonal dodecahedrons, 28 ; sign, 29. 

Tufa, calcareous spar, 365. 

Tungsten, test of, 128; see Wolfram. 

Turquoise, hardness of, 80 ; described, 829 ; 
1. true oriental; 2. bone, or occiden- 
tal, 330. 

U. 

Ultramarine, made from lapis lazuli, 824; 

hosv prepared, 325; imitations, 826, 
Uranium, test of, 128. 

V. 

Vanadium, test of, 128. 
Variolite (felspar), 314 
Venus' hair, 261. 
Volcapic glass, or obsidian, 809. 



464 



/ 



w. 



"Water in rock crystal, analysis of, 265. 
Weiss and Rose, system of crystalliza- 
tion, 21. 
Wernerite. double refraction o^ 88. 
Wolfram, 68; test of, 120; see Tungsten. 
Wollaston's goniometer, 58. 
Woodstone, 277. 



Y. 



Tttria, test of; 128. 



/<^i/ 

X 



z. 

Zinc, blend, 64; test of 124 

Zircon, ' double refraction of, 8T ; test of, 

123; described, 244; same as hyacinth, 

ib.; varieties, 245. 
Zuisang (lapis lasuli), 825. 



